Appendix B: Types of Engineer Units and Their Functions
Airborne Aviation Battalion
29 officers, 50 enlisted men.1 Equipped with light machinery, this unit prepared captured airdromes, usually located behind enemy lines, for early use by Army Air Forces. It was sometimes flown in to clear landing strips when regular aviation battalions, because of their heavy equipment, could not be used.
Aviation Battalion
33 officers, 744 enlisted men. The basic engineer construction unit of the Army Air Forces. It was completely equipped to construct an airfield and all its appurtenances. It might also be called upon to camouflage, maintain, and defend airfields.
Aviation Company, Separate
5 officers, 171 enlisted men. Similar in organization to a company of a combat battalion, but with more machinery for runway construction.
Aviation Regiment
66 officers, 1 warrant officer, 2,160 enlisted men. This large unit was organized, trained, and equipped in the early days of the defense buildup. It constructed, repaired, maintained, camouflaged, and defended airfields wherever such work was concentrated in a small area. The battalions of the regiment were the same as regular aviation battalions.
Headquarters and Headquarters Company, Base Depot Group
11 officers, 2 warrant officers, 62 enlisted men. Provided the overhead needed to supervise the operations of an engineer base depot group. Normally such a group was at or near a port of debarkation. The headquarters and headquarters company with its attached troops operated either the engineer section of a general base depot or an engineer base depot. One or more of the following units were attached: base depot company, heavy shop company, base equipment company, parts supply platoon or company, gas generating unit, quartermaster truck company.
Base Equipment Company
5 officers, 168 enlisted men. This unit, usually located at or near an engineer
depot, made various types of heavy construction equipment available to engineer units on a loan basis. Skilled operators were sometimes sent with the equipment.
Camouflage Company, Separate
5 officers, 62 enlisted men. Usually assigned to a task force or independent corps, supervised and inspected camouflage work, discipline, and training; experimented with new camouflage methods; and helped troops camouflage their areas.
Combat Battalion
29 officers, 3 warrant officers, 605 enlisted men. This was the Engineer component of the triangular infantry division. It increased the division’s combat effectiveness by means of general engineer work, including construction of roads and bridges, the clearing of mines, and the destruction of obstacles. The unit thereby helped make it possible for the infantry to advance, and by laying mines, erecting obstacles, and using demolitions helped the infantry thwart an enemy attack.
Combat Company, Separate
4 officers, 176 enlisted men.. Usually employed in improving routes of communication. The amount of work the company could do with its men and tools alone was relatively small.
Headquarters and Headquarters Company, Combat Group
15 officers, 69 enlisted men. The primary mission of this unit was to supervise the operations of corps and army combat engineer troops. The composition of the group was determined by the engineer mission and the units and facilities available.
Combat Regiment
39 officers, 1 warrant officer, 908 enlisted men. The Engineer component of the square infantry division, the combat regiment performed the same engineer work for the square division that the combat battalion performed for the triangular division.
Construction Battalion
29 officers, 2 warrant officers, 869 enlisted men. Organized in 1943, this unit, capable of operating independently or as part of a group, was the equal of an aviation battalion in earth-moving capacity and of a Navy construction battalion in equipment and grades for skilled personnel. It had more heavy equipment and higher grades for its skilled personnel than a general service regiment.
Headquarters and Headquarters Company, Construction Group
13 officers, 1 warrant officer, 80 enlisted men. Organized to supervise the operations of from three to six construction battalions.
Depot Company
7 officers, 202 enlisted men. Its primary mission was the operation of an engineer depot or other engineer supply point in a theater of operations. It
sometimes was a part of a large special engineer depot or the engineer section of a general depot; sometimes it operated as a separate engineer supply unit.
Dredge Crew
Varying from 5 officers, 4 warrant officers, 47 enlisted men to 6 officers, 4 warrant officers, 57 enlisted men, this unit dredged rivers, harbors, and channels.
Dump Truck Company
4 officers, 103 enlisted men. Its principal mission was to assist other engineer units by furnishing transportation for the movement of heavy materials. This unit was usually attached to engineer units engaged in road and railroad construction involving earth moving, clearing, grading, and paving.
Engineer Squadron
14 officers, 441 enlisted men. This unit, the Engineer component of the cavalry division, did work comparable to that performed by the combat battalion for the infantry division.
Headquarters and Headquarters Company, Forestry Battalion
8 officers, 2 warrant officers, 82 enlisted men. The headquarters and headquarters company supervised 3 or more forestry companies (each with 5 officers and 150 enlisted men) whose job it was to supply lumber and other forest products from woodlands in or near a theater of operations. The companies either set up and operated the sawmills with which they were equipped or they used sawmills already in the area.
Foundry Team
1 officer, 16 enlisted men. This team was capable of producing molten metal in the following quantities:
Cast iron—about 108 lbs. per hour
Steel—about 100 lbs. per hour
Bronze—about 132 lbs. per hour
A team was normally assigned to a heavy shop company.
General Service Regiment
39 officers, 11 warrant officers, 1,221 enlisted men. Performed general engineer work—especially that requiring a fair amount of skilled labor—throughout the army service area and communications zone of a theater of operations. A general service regiment, with its large headquarters organization, large number of specialists, and special equipment, plus the fact that it remained a longer time in an area, could undertake extensive and permanent work. General service regiments could be reinforced with other engineer units.
Heavy Ponton Battalion
12 officers, 462 enlisted men. Transported and maintained four units of heavy ponton equipage, 25-ton M1940, with which it constructed bridges and rafts, sometimes with the assistance of other engineer troops. In an extensive river crossing operation, the battalion was attached to a corps to provide a bridge capable of supporting heavier loads.
Heavy Shop Company
6 officers, 165 enlisted men. A semi-mobile unit, the heavy shop company performed fourth echelon maintenance on all equipment for which the Corps of Engineers had maintenance responsibility. Fourth echelon maintenance included rebuilding a unit’s equipment, overhauling the attachments and accessories, doing emergency overhaul of major units, and recovering equipment from the battlefield, reclaiming, and salvaging it.
Light Equipment Company
4 officers, 114 enlisted men. Furnished supplementary equipment with operators to engineer combat battalions and operated as a replacement pool for construction equipment. Light equipment companies were attached to corps or army.
Light Ponton Company
6 officers, 215 enlisted men. Organized and trained to maintain its stream-crossing equipage, to construct floating bridges and rafts, to guard and maintain completed bridges, to regulate traffic thereon, and to dismantle bridges and rafts.
Maintenance Company
6 officers, 185 enlisted men. A mobile unit, the maintenance company had as its primary mission third echelon maintenance of all equipment, including that used by other arms and services, for which the Corps of Engineers had maintenance responsibility. Third echelon maintenance included the making of minor repairs on a unit’s equipment.
Map Depot Detachment
1 officer, 11 enlisted men. Received, stored, and issued maps. This unit was adequate to provide map depot facilities for one base section.
Model Making Detachment
1 officer, 18 enlisted men. Constructed scale models of terrain to assist air and ground forces in planning. Normal attachment was to a topographic unit since photo processes were used in model making. The unit was assigned as directed by the commander of the theater of operations.
Parts Supply Company
6 officers, 168 enlisted men. Established and operated an engineer spare parts supply depot and other spare parts supply agencies. This company was a nonmobile unit which operated as part of the engineer depot organization of a base installation. It could not operate as a separate supply unit unless it was furnished with motor transportation.
Petroleum Distribution Company
7 officers, 209 enlisted men. The primary mission of this unit was to design, construct, operate, and maintain military pipeline systems for transporting, distributing, and storing gasoline in a theater of operations.
Pipeline Operating Detachment
officer, 24 enlisted men. Organized and equipped to operate a bulk petroleum terminal consisting of 50,000 barrels of tankage with the necessary tanker unloading facilities and a three-pump station pipeline system.
Photomapping Team
2 officers, 78 enlisted men. This team was equipped to perform original topographic mapping from aerial photographs. It was normally attached to a topographic unit having planning, computing, and reproduction facilities; it was sometimes used to increase the capacity of a base topographic battalion.
Headquarters and Headquarters Company, Port Construction and Repair Group
17 officers, 255 enlisted men. This unit, with its attached units, made ready for use the facilities of ports of debarkation in a theater of operations, and performed work required for the improvement or expansion of such ports, exclusive of harbors.
Railway Operating Battalion
18 officers, 803 enlisted men. Operated trains and yards of a railway division, maintained tracks and structures, and repaired equipment. A battalion might also be assigned the operation and maintenance of a large railway terminal or regulating station. Railway battalions were transferred to the newly organized Transportation Corps in November 1942.
Railway Shop Battalion
20 officers, 642 enlisted men. Handled heavy shop work for several railway operating battalions. These units were transferred to the newly organized Transportation Corps in November 1942.
Separate (Labor) Battalion
22 officers, 1,197 enlisted men. Usually assigned to armies or to GHQ, the separate battalion performed general engineer work throughout a theater of operations. It was frequently attached to reinforce other engineer units in whole or in part.
Technical Intelligence Team, Combat
Technical Intelligence Team, Research
officer, 3 enlisted men; 3 officers, 6 enlisted men. Both kinds of teams operated in a theater of operations. The combat team furnished technical intelligence information for use in the theater; the research team sent information to the zone of interior for further study.
Topographic Battalion, Army
19 officers, 3 warrant officers, 404 enlisted men. This unit had the mission of furnishing adequate map information for tactical and strategical requirements for an army and established and extended horizontal and vertical control for army and corps requirements. It was the organization trained and equipped to prepare and reproduce photomaps, maps of limited areas, overlays, and sketches, and to revise and reproduce existing maps.
Topographic Company, Corps
5 officers, 113 enlisted men. Reproduced maps in quantity in forward areas, distributed them to corps troops and to divisions, and established and extended the ground control required for coordination of field artillery fire. When aerial photographs were made available, corps topographic companies used them to prepare photomaps and to revise existing maps. Initial requirements of the corps were met by the corps topographic company, which rapidly prepared and supplied map information, particularly the hasty type of map substitute.
Topographic Battalion, GHQ
29 officers, 767 enlisted men. Its primary mission was the reproduction at the outbreak of hostilities of existing maps of the theater of operations and of such maps, sketches, and drawings of permanent character as might be needed thereafter. Its reproduction functions approached those of a permanent establishment and its equipment was relatively heavy and immobile. It prepared maps by photogrammetrical methods as the situation required. It sometimes reinforced army topographic battalions.
Topographic Company, Aviation
8 officers, 141 enlisted men. Revised, prepared, and reproduced maps, aeronautical charts, navigation charts, target charts, and mosaics for the Army Air Forces.
Treadway Bridge Company
4 officers, 134 enlisted men. Transported, maintained, and constructed bridges with its steel treadway equipage, guarded, maintained, and regulated traffic thereon, and dismantled completed bridges.
Headquarters and Headquarters Company, Water Supply Battalion
10 officers, 2 warrant officers, 112 enlisted men. A headquarters and headquarters company supervised several water supply companies (each with 4 officers and 116 enlisted men), whose principal mission was the procurement, purification, and distribution of potable water to troops in areas where the local supply was inadequate. It might also be charged with the repair of water plants and with developing water supply sources. A water supply company could operate alone or as part of a battalion.