Here is the current draft of the Combat Engineers rules.
Posted drafts are likely to flex a little bit as discussion continues on the Ogre forums.
Vulcans and Combat Engineers
Draft of 8-25
3.02.3 – Combat Engineers (CE). Combat Engineers are specialist infantry with skills to alter the battlefield and aid in the survivability of other units. Combat Engineers may attempt to perform an engineering task in place of a combat action during the Fire Phase of a turn. Combat Engineers stacked in the same hex with other units can provide assistance with difficult terrain. Except as noted in section 14.00 (Combat Engineering), squads of Combat Engineers are treated for all purposes like regular infantry.
11.04.5 – Combat Engineering Attacks. Combat Engineers and Vulcans do double damage against stationary structures. This is in addition to any other modifiers, as described in section 11.00 of the Ogre Designer's Edition rulebook. Thus, attacks at range cause damage equal to four times the squads or Vulcan’s attack strength, and damage done during a building overrun is sixteen times the attack strength. Other units that are stacked with the Combat Engineers or Vulcan during the attack on the building also do double damage!
14.00 – Combat Engineering.
Combat Engineering is the art and science of altering a battlefield to support friendly forces or thwart enemy ones. This may be done by:
- aiding the movement of friendly units;
- impeding enemy movement;
- or directly attacking or defending.
Combat Engineers are infantry with specialized training; Vulcans, aided by their Heavy Drones, are the Ogre equivalent. In these rules, the term 'Sapper' encompasses Combat Engineers, Vulcans, and Heavy Drones.
In the world of Ogre, there are two types of tasks that may be performed on the nuclear battlefield: engineering tasks and Vulcan tasks. During a game, either Combat Engineers or Vulcans may perform engineering tasks, whereas only Vulcans and/or their Heavy Drones may perform Vulcan tasks. Some tasks succeed automatically after a specific amount of time, while others require a roll to determine whether the task was completed.
Unless otherwise specified, a Vulcan with both arms and a full complement of light drones is the equivalent of four Combat Engineer squads for human-capable tasks. Each Heavy Drone adds another two squads.
14.01 – Ogre Vulcan. The Vulcan repair and recovery cybertank was the Combine's solution to the logistic problem of delivering an Ogre quickly. An Ogre could be shipped in modules, sea-freighted, or even airdropped, and assembled in the field. But there were some places where human assembly crews couldn't go . . .
The Vulcan was built on a Mk. III-B chassis, with huge three-fingered manipulator arms replacing the main batteries. For purposes of size and ramming, treat it as a Mark III. Lighter than a Mark III, it was significantly faster: It starts with a move of 4 hexes. It has 48 tread units. Vulcans are worth 150 points or more, as determined by the scenario.
The manipulator arms are intimidating, but they are not effective weapons against anything faster or better armored than a human being. Each arm may be targeted separately, and has D2.
Each Vulcan carried scores of small drones for maintenance and assembly work. Usually a Vulcan would be accompanied by one to four heavy maintenance drones . . . basically, a Heavy Tank chassis with a single large manipulator arm, which the Vulcan could use as one of its own. A Vulcan may control up to four Heavy Drones at once, in addition to its swarm of light specialist drones.
The Vulcan was not intended for combat at all. The original design was unarmed, but the generals – and the self-aware Ogres already in existence – insisted on some self-defense capability in case of surprises. However, all it has are two secondary batteries and six AP guns. The Vulcans were all self-aware, and they also knew perfectly well that they were scarce and hard to replace. Therefore, they exhibited even more caution than other self-aware units.
Vulcans also got along better with humans than did most Ogres. The Vulcans worked closely with human techs, considered "their" crews to be valuable assets, and went to surprising and ingenious lengths to protect them. And, while many Ogres displayed a warrior's frightening sense of humor, Vulcan humor tended to be actually funny, even silly. How much of this was "real" is anyone's guess, but the result was that experienced tech crews could work efficiently, and even comfortably, with Vulcans, and Vulcans often became unofficial liaisons between human and Ogre elements.
14.01.1 – Cargo Capacity. The Vulcan has enough internal cargo space to carry a dozen Ogre missiles, or two squads of battlesuited infantry if they're not claustrophobic, or six LADs on pallets, or an equivalent load. This storage space will survive as long as the Ogre does. The Vulcan's top cargo area can carry a unit or units totaling Size 4, or four battlesuit squads, or 12 LADs on pallets, or two dozen Ogre missiles, but these are exposed. Combat units will be exposed to spillover fire from anything that hits the Vulcan. Items on pallets, missiles, and so on will simply be destroyed if the Vulcan is hit. The rear cargo area is accessed by a retractable ramp, which was frequently useful in vehicle recovery.
14.01.2 – Vulcan Tasks: Maintenance and Assembly. The list below is not exhaustive; it covers a few jobs a Vulcan might be given, but referees should extrapolate from this to set logical times for anything that a Vulcan could reasonably do.
These times assume "two arms" – an undamaged, unassisted Vulcan with its swarm of light drones.
Reduce time by 1/3 (i.e., a 6-turn job takes 4 turns) if there is one more arm helping, whether it belongs to a Vulcan or a drone. Halve times if two arms (both arms of a Vulcan, or two drones) are helping. For most maintenance tasks, that's the largest group that can do the job efficiently. Too many helpers might get in each others' way, so referees need not assume that "more is better." Combat Engineers or skilled human techs could also assist a Vulcan, but these are topics best left for a refereed situation.
Some jobs and their associated times:
- To secure a damaged armor unit in the field and winch it onto the top cargo area: six turns.
- To unload all palleted cargo from either the top or interior, or to load new cargo that is palletized and ready to go: six turns.
- To load or unload a single specified item: one turn.
- To assemble an Ogre from its modular parts:
- Mark II – 12 turns
- Mark III – 30 turns
- Mark III-B – 42 turns
- Mark IV or V – 60 turns
- Vulcan – 72 turns
- Ninja – at least 75 turns
Mark VI units were never delivered in modular form. Ogres larger than a Mark III-B are not normally built under combat conditions, and Vulcans and Ninjas were almost always delivered to safe areas for assembly. They were too scarce to drop into a potential combat zone unless a great deal was at stake. But scenario writers will find reasons . . . If fire is directed at an unfinished Ogre, treat all 'D' results as 'X'. An unfinished Ogre cannot shoot back.
14.01.3 – Vulcan Heavy Drones. Vulcan Heavy Drones have one giant manipulator arm and no weapons, and move and defend as Heavy Tanks. A Heavy Drone can pick up and carry one cargo pallet across its prow. Picking it up or putting it down takes one turn.
Without a Vulcan to command it, a Heavy Drone is merely a medium-sized construction crane that can accept voice commands. They are capable of great precision, but have no common sense, let alone intelligence. For engineering work, an unaccompanied Drone is worth two Combat Engineering squads, but only if at least one Combat Engineering squad is in the same hex or if the Vulcan is in the same or an adjacent hex and controlling it via a drone channel.
Drones are worth 16 victory points each. This reflects not their combat value, which is negligible, but their scarcity and the fact that they act as a "force multiplier" for the Vulcan.
14.01.4 – Vulcan Combat Drones. Although the Vulcan wasn't intended to control vehicles in combat, its four drone-control channels could be used to communicate with the onboard computer systems of a regular armor unit. Those systems, unaided, will allow an armor unit to move intelligently over short distances, and to attack at half strength; that's why disabled units defend normally and attack at half strength while the crew recovers.
With a Vulcan in the loop, an armor unit can become, in essence, a combat drone, and operate normally with no crew at all. Humans are used for crew not because they are better, but because they are far cheaper than combat-capable AI systems! Each such unit takes one of the Vulcan's four heavy-drone slots.
14.01.5 – Duckling Drones. If the Vulcan is not trying to do any more with a controlled unit than keep it nearby and drive it along, it may have up to four units of any type in each drone control "channel." So a Vulcan might be followed by up to 16 "ducklings," all within one hex of the Vulcan. These ducklings may be Heavy Drones, combat units, trucks and/or hovertrucks, or any combination of the above. Of course, not being at all stupid, the Vulcan would probably put the ducklings in front if the area were not secured.
In a combat situation, the "ducklings" fight at half strength. They must either stay within a hex of the Vulcan or stop moving completely, in which case they are considered disabled. (Of course, if there is a live crew aboard, it can take over.)
In most surprise combat situations, a Vulcan with ducklings would simply take full control of the most useful and drop the others to fend for themselves as disabled units. The Vulcan determines which four ducklings are under active control at the beginning of each turn. It can switch which four it controls each turn. If a group of ducklings is overrun, the Vulcan can take active control of four of the units for the duration of the overrun; the remainder of the units should be treated as disabled.
14.02 – Engineering Tasks. Combat Engineers and Vulcans may perform various tasks on the battlefield. These tasks fall into two general categories: building things (repairing roads, building bridges, making entrenchments) and destroying things.
To attempt to perform an engineering task, one or more Combat Engineer squads and/or Vulcans must start their turn in the hex they wish to perform the task, and stay in that hex for the duration of that turn. Tasks are assigned a number that must be rolled on one die for success. This assumes a single squad of Combat Engineers. Extra squads, or Vulcans and their drones, can help. Each squad of engineers allows one extra die to be rolled. A Heavy Drone gives two dice; a Vulcan with two arms gives four.
Example: if three squads of Combat Engineers are attempting to bridge a stream, three dice are rolled for the attempt; a single Heavy Drone (controlled by a Vulcan elsewhere) attempting to bridge that same stream on its own would roll two dice; a lone Vulcan attempting the same task would roll four dice. If a 6 is rolled on any die, the task is successfully completed.
There is no limit as to the number of Sappers that may help to perform any specific task on a turn, but each Sapper may only make one attempt per turn, and the specific task may be attempted only once per turn regardless of how many Sappers participate in the attempt. Attempting a task counts as that squad's "attack" for that turn, and is made during the Fire Phase.
14.02.1 – Placing Mines. If mines are available in the scenario, any Sapper may attempt to place a mine, as per Ogre Designer's Edition section 13.04. Placing a mine successfully requires a roll of a 5 or 6, regardless of the unit. The mining player should make note of the hex within which a mine is placed and, if applicable, if it is on a road or rail.
There is no consequence for a failed roll, and the Sapper may try again next turn.
14.02.2 – Disarming Friendly Mines. Any friendly Sapper in the mined hex can automatically disarm successfully placed mines without requiring a roll at the start of their turn. Disarming friendly mines does not require an action during the Fire Phase (it is done during the Recovery Phase), but re-arming them does require the "placement" action during the Fire Phase. This allows friendly units to traverse the mined hex safely on their turn. Rearming mines that have already been placed is an automatic success during the Fire Phase.
14.02.3 – Detecting Mines. By using drones and the specialist tools built into their battlesuits, Combat Engineers may attempt to detect mines in any of the hexes surrounding the one they're occupying. The chance of success is directly related to the number of hexes they attempt to search per turn. To detect any mines in the searched hexes, they need to roll on one die a number greater than the number of hexes they are searching. For example, to search three hexes, a Combat Engineer squad would need to roll a 4+ on one die to succeed. A successful roll detects all mines in the hexes being searched
A Vulcan has state-of-the-art detection equipment, giving it advanced awareness of mines and other hidden units. A Vulcan searches for mines as above, but rolling two dice. Heavy Drones are not equipped to detect mines and cannot aid in these rolls.
Whenever a Vulcan is about to enter a hex with a mine or a hidden unit, the opposing player must acknowledge the presence of a mine (or hidden unit) within the hex. The Vulcan may then choose to either not enter the hex and move elsewhere, or continue into the hex.
Once a mine is detected, a Sapper may enter the hex without fear of detonation. Additionally, other units may traverse the hex without fear of detonating the mine as long as the Sapper is in the hex. Units will lose the road bonus when traversing a mined road, however. The Sapper may not fire or perform any other task during the turn it assists in mine avoidance.
The mine is still active, and will be dangerous to others once the Sapper leaves the hex.
14.02.4 – Disarming Enemy Mines. A Sapper may disarm enemy mines once they are discovered. Successfully disarming an enemy mine requires a roll of 5+. A failed roll does not mean that the mine exploded; rather, it simply means that it will take at least another turn to successfully disarm that mine. Disarming a mine destroys the mine without detonating it.
14.02.5 – Building Entrenchments. Sappers may protect infantry in clear, forest or rubble terrain through entrenching. A die roll determines how many squads the entrenchments will protect. On a roll of a 1-4, one squad-equivalent of Combat Engineers creates an entrenchment that can protect one squad of infantry. A roll of a 5 creates an entrenchment that can protect two squads, and a roll of a 6 creates a 3-squad entrenchment. Any number of CEs, Vulcans, and drones may help, as above. The single best result from the die rolls represent the extent of entrenchments created on that turn.
Players should place a token (penny, etc.) in the hex per entrenchment to depict the location and number of the entrenchments. Up to 15 entrenchments may be created in a hex, at a maximum of 3 squads' worth per turn.
Entrenchments double the defense strength of infantry within the entrenchment in clear terrain, and triple the defense strength of infantry within the entrenchment in forest or rubble terrain. Additionally, if the result on the CRT is a "D," the lost squad comes from any units not entrenched prior to those entrenched; randomly determine from the squads that aren't entrenched.
Infantry, including Heavy Weapon Teams, can fire normally from entrenchments. For scenarios using the Ogre map, i.e., ramming rules instead of overrun rules, entrenched infantry are not reduced when an Ogre first enters their hex. The Ogre may spend an additional MP to remain in the hex and reduce the infantry normally (see section 6.06 in Ogre Designer's Edition). Thus it is possible for an Ogre to move into or through the hex without reducing the entrenched infantry.
Entrenchments have no effect on vehicles or movement. Entrenchments in any terrain other than clear, forest or rubble offer no benefit.
Infantry from either side may use entrenchments simply by moving into the hex, as long as no enemy units are present.
Each hex with entrenchments has a defense strength of 4 and may be attacked separately, as though it were a unit. A 'D' result reduces the number of entrenchments in the hex by one, in the same manner as infantry reduction. An 'X' result destroys all entrenchments in the hex. Calculate spillover fire normally on any units in an entrenched hex. Spillover fire has no effect on entrenchments themselves.
14.02.6 – Terrain Leveling. Repairing roads cut in a single spot, bridging streams, or creating improvised GEV ramps are tasks that require some degree of tools and materials beyond what a squad would be carrying on the battlefield. A player picking one or more Combat Engineer squads may choose a truck or hovertruck per squad with the needed gear to perform these tasks. These trucks are not specialized engineering vehicles; they are simply loaded with equipment and supplies. The cost is 1 VP cost per truck or 2 VP per hovertruck. Vulcans and Heavy Drones have these tools and supplies automatically.
One or more Combat Engineer squads with the associated truck(s), or a Vulcan and/or Heavy Drone, may attempt to repair a cut road, bridge a stream, or build a GEV ramp. The truck needs to start, and stay, in the hex for the entire turn with the Combat Engineer. A separate truck is required for each squad that attempts the task. A roll of 6 is required to succeed.
Combat Engineers may NOT clear roads that are cut due to damaged or rubbled terrain during a game; the damage is too extensive (see Ogre Designer's Edition section 13.01). Combat Engineers may not repair railroads during the game, as the task is too specialized. These are tasks specific to Vulcans and their Heavy Drones, as described under 14.03 – Vulcan Tasks.
14.02.7 – Grading Ridges. By planting charges in the right spot, a low point may be created in a ridge to allow units to pass through the ridge as if it were not there. Any Sapper may attempt this task, and other Sappers may aid as usual; the attempt succeeds on a roll of 5 or greater. A clear hexside marker should be placed over the ridge on the map.
14.02.8 – Destroying Ogres. An Ogre that has lost all its weaponry but can still move remains a threat on the battlefield. Combat Engineers may destroy it by placing specialized nuclear charges at critical points on the Ogre. To do so, they must move into the hex containing the Ogre; rather than an overrun attack, this constitutes the Combat Engineers climbing onto the weaponless Ogre. Successfully detonating a "coup de grace" charge requires a roll of 4, 5 or 6. The Combat Engineer Squad remains in the hex. Should the attempt fail, it may be attempted again on a subsequent turn.
Only Combat Engineers may destroy a mobile but defanged Ogre. Against Ogres that still have AP guns, a Vulcan (or Heavy Drone guided by a Vulcan) may also plant an execution charge. This requires a roll of 4+ to succeed if the Ogre is immobile, or a 6 to succeed if the Ogre can still move; it will try to evade, and on its own turn will probably ram the attacking unit.
|Task Table 1
|1d6 roll for success
|Placing a mine
|Detecting a mine
|Disarming an enemy mine
|Repair road/bridge stream/build ramp
|Finishing off an Ogre
|4+ or 6
14.03 – Vulcan Engineering Tasks. Some jobs are too big to be performed by humans on the nuclear battlefield within the time limits required and without extensive machinery. Vulcans and their Drones handle Vulcan tasks the same way that humans handle regular engineering tasks. The difference is in the number of dice available to roll for success and whether one or more Heavy Drones are required for the attempt.
A Vulcan or Heavy Drone attempting to perform a Vulcan task must start the turn in the hex they wish to perform the task, and stay in that hex for the duration of that turn. Tasks are assigned a number that must be rolled on one die for success. A Vulcan rolls two dice for success; each Heavy Drone that assists contributes one die to the attempt. If any one die rolls the required number, the task succeeds. Some Vulcan tasks require Heavy Drones; these required Drones do not add dice to the success roll. As they are required, their presence is factored into the two dice the Vulcan rolls. Additional Heavy Drones may assist the Vulcan or Heavy Drone attempting the task, adding an additional die per Heavy Drone above the required number to attempt the task.
14.03.1 – Assist 'Stuck' Units. A Vulcan may remove units stuck in swamp hexes. First, the Vulcan (and possibly, one or more drones,) needs to get to the stuck unit. This requires the Vulcan to enter the swamp hex. Although it may attempt to do so as any other unit by just entering the hex, it risks getting stuck itself if it rolls a 1 or 2 on one die. To avoid getting stuck, a Vulcan may make a prepared entrance into the hex. The Vulcan player rolls one die, and the result is the number of turns the Vulcan (and any accompanying units) must wait prior to entering the hex. The other restrictions of a swamp hex still apply.
On the turn following its entrance into the swamp hex, the Vulcan may attempt to free the stuck unit. This requires a roll of a '6' on one die. A Vulcan may attempt to free any unit size 5 or smaller on its own. For every step up in size, one Heavy Drone is required to assist in the attempt. Additional Heavy Drones may assist in the attempt above the number required to make the attempt. Example: a Mark III (size 7) took an ill-advised jaunt through a swamp hex and got stuck. Freeing this Ogre requires the Vulcan and two Heavy Drones; a third and/or fourth may join the effort, thereby adding one or two additional dice to the one die the Vulcan rolls for success. Heavy Drones may not attempt to free a stuck unit on their own. A Vulcan may not attempt to free itself should it become stuck, and Heavy Drones that are stuck may not assist in freeing other units until they themselves are unstuck.
14.03.2 – Repair Cut Rail. A Vulcan or Heavy Drone may repair a rail line that has been cut. The Vulcan needs to start, and stay, in the hex for the entire turn to attempt this task. Clearing a "Road Cut" marker on a rail line requires a roll of a 5 or 6 to succeed. Vulcans may not repair rails that are cut due to damaged or rubbled terrain during a game; the damage is too extensive (see Ogre Designer's Edition section 13.01).
14.03.3 – Clear Roads in Damaged Terrain. A Vulcan may clear roads that are cut due to damaged terrain (see Ogre Designer's Edition section 13.01). Clearing damaged terrain requires either a Vulcan or at least two Heavy Drones. A roll of 4 or greater is needed to succeed at this task. Additional Heavy Drones may assist in the attempt, adding dice to the success roll. This task is separate from mending a road that has been deliberately cut in one spot; that smaller level of repair is covered in 14.01.5, Terrain Leveling. The damage in rubbled terrain is still too extensive for a Vulcan with Drones to clear or repair within the confines of the game.
14.03.4 – Reload Missiles. If a Vulcan is carrying spare missiles, that Vulcan or an accompanying Heavy Drone may reload either internal or external missile launchers. External missiles may only be reloaded if they were fired; the launcher is too damaged to reload an external missile that was destroyed in place. Reloading an external missile is an automatic success, although the action still requires the Vulcan to be stationary in the hex for the full turn. The Vulcan may reload one missile per turn. The Vulcan is required to attempt this task as the missiles as stored in (or on) it. However, if Heavy Drones are available, an additional missile may be reloaded per Drone, per turn.
Reloading internal missiles is more complicated, and requires at least one Heavy Drone to attempt. This task succeeds on a roll of 5 or greater. The Ogre being reloaded must have at least one functioning missile rack. Only one internal missile may be reloaded per turn, regardless of how many Heavy Drones are available and assuming a successful attempt. Additional Heavy Drones may assist in the success roll attempt, however.
14.03.5 – Weapon Field Repair. Usually an Ogre weapon that receives an 'X' result from an attack is far too damaged to repair in the field. On occasion, the damage is light enough that a Vulcan may attempt to repair it in the field. Whenever an attempt is made to repair a weapon that was destroyed, roll one die. On a 5 or 6, the damage is light enough that an attempt to repair it may be made. On any other result, a notation should be made on the record sheet that this weapon is beyond field repair. Destroyed external missiles and missile racks are always too damaged to attempt field repair.
If an attempt may be made to repair the weapon, the task requires a Vulcan; drones cannot help. Only one die is rolled for each attempt, and a 6 is required for success.
14.03.6 – Tread Field Repair. Ogre treads may be repaired in the field as well. Either a Vulcan or a Heavy Drone may attempt to repair treads: two dice for a Vulcan, one for each drone. For every 6 that is rolled during the attempt, one tread is repaired.
14.03.7 – Create Revetment. Revetments are prepared positions for armor units and infantry that can add to their defensive strength. In years past they were earthen embankments that could deflect or absorb incoming rounds. In the nuclear world of Ogre, the best defense is . . . still to dig a hole in the ground. Revetments have no inherent movement value and may not be moved by other units.
Revetments add +1D to the defense strength of a combat unit. This bonus is added after any terrain bonus multiplier. Spillover fire rules are applicable to other units sheltering within one.
Revetments are static positions, and can be targeted independently. They have a defense strength of 2. See section 7.12 in Ogre Designer's Edition. Revetments may receive terrain defensive bonuses like other armor units, (e.g. they have a defense strength of 4 in a town hex). Only an 'X' result has an effect on revetments; a 'D' is considered a 'NE' for game purposes.
Revetments come in two sizes: small and large. A small revetment can offer protection to a unit size 3 or smaller, whereas a large revetment protects a unit or units up to size 5 (see Size Table on page 14 of the Ogre Designer's Edition rulebook). More than one unit may occupy the revetment as long as the total size is less than the size of the revetment and stacking limits are observed. Example: up to three Light Tanks (size 1 each) could all occupy a small revetment and benefit from the +1D.
Entrenchments may be built within a revetment. In this case, the entrenchment benefit is calculated prior to the revetment benefit in the same manner as any other terrain bonus.
|Task Table 2
|Req. Heavy Drones
|1d6 roll for success
|Free Stuck Units
|Repair Cut Rail
|Clear Road in Damaged Terrain
|Reload Internal Missile
|Weapon Field Repair
|6 (one die only)
|Create Small Revetment
|Create Large Revetment
14.04 – Terrain Assistance. Sappers that travel with other units may offer assistance in navigating through, and recovering from, hazardous terrain. For armor units to obtain this benefit, the Sapper(s) must remain stacked with the armor units obtaining the benefit for the entire turn. Combat Engineers offering this benefit may not fire or perform other engineering tasks on the turn that they are performing this assistance; Vulcans do not have this restriction.
14.04.1 – Terrain Navigation. Combat Engineers and Vulcans stacked with units traveling through swamp or rubble (or forest, for GEVs) may reduce the chance of those armor units becoming disabled or getting stuck by 1. So a GEV travelling through a forest hex is disabled only on a roll of 1. Likewise, a heavy tank entering a swamp hex becomes permanently stuck only on a roll of 1. Units entering hazardous terrain still must end their movement for the turn as described for swamp terrain. Combat Engineers are not riding units during this assistance; they must be dismounted. Note that this benefit is independent of the number of Combat Engineer squads stacked with the units, (i.e. additional Combat Engineer squads do not reduce the risk further). All units stacked with the Combat Engineer squad or Vulcan may benefit from this advantage. Any Combat Engineers that did not offer Engineering Assistance, attempt an Engineering Task, or engage in combat may offer Engineering Assistance to GEVs during their Second Movement Phase, provided the Combat Engineers were stacked with the GEVs during the entire turn.
14.04.2 – Recovery. Sappers beginning a turn stacked in the same hex with a unit previously disabled by terrain may add 1 to the recovery roll per Combat Engineer squad-equivalent stacked with the unit (i.e., a unit recovers on a roll of 1-5, not 1-4, with one Combat Engineer squad stacked in the hex, and automatically recovers with two squads or one Vulcan or Heavy Drone). Unlike most sapper actions, this takes place in the movement phase, meaning the sappers may fire normally if necessary, or even take a regular sapper action.
Each Combat Engineer squad may only assist one unit per turn, but more than one squad may be assigned to assist a disabled unit.
The sappers may move normally on that turn if the recovery roll succeeded or was automatic. Otherwise, they spend the whole movement phase in the unsuccessful recovery attempt.