US Marine Corps Pacific Theater of Operations 1944–45

Accurate maps of islands became even more scarce as US forces thrust into the Japanese Mandated Territory. Aerial and submarine photography became even more important in order to obtain this information and make maps from. The ability to access the number and types of Japanese troops on an island improved dramatically. Submarine through-the-periscope photography of beaches was important in that it provided a ""marine's eye view"" of the landing beaches as they would see from amtracs. Low oblique aerial photography was not completely perfected until just before the Iwo Jima landing. The collection and assessment of data improved to the point that there was too much to process and disseminate.
In order to deal with this the Marines gradually enlarged the intelligence sections at all echelons. To produce tactical maps, aerial photographic mosaics, island terrain models, and terrain studies, the Marines organized a Company D in the 1st and 2d Separate Engineer Battalions on Guam in late 1944. The 141-man, four-platoon companies were redesignated the 1st and 2d Separate Topographic Companies in February 1945 and assigned to IIIAC and VAC HQ&S Battalions. The HQ companies of divisional engineer battalions were assigned additional personnel to provide similar products.