Francis X. Popper plotting hydrographic survey in New Guinea. Regimental navigator for Army amphibious engineers.

Following WWI, the C&GS reverted to its role of peaceful surveyor and chart maker of the Nation. The young men who came into the Survey during this period spent years developing expertise in land surveying, sea floor and airways charting, coastline mapping, geophysics, and oceanography. This expertise was combined with the hardships of a lifestyle that was characterized by years in survey field assignments or attached to survey vessels.

With the advent of the Second World War, once again over half of the commissioned officers of the C&GS were transferred to either the Army, Navy, or Marine Corps. Of the C&GS civilian work force, approximately one-half, slightly over 1,000, joined the armed services. Those remaining on the home front were engaged almost exclusively in activities related to the prosecution of the war. Three officers who remained in the C&GS and eleven members of the agency who had joined other services were killed during the course of the war.

Officers and civilians of the Survey served in North Africa, Europe, and throughout the Pacific. These individuals served with distinction, earning the respect of the highest echelons of the armed services. Members of the Survey shared the danger, hardship, and years of separation from loved ones that were common to all services. As the C&GS'ers were but a small portion of the men and women under arms during this period, there is no claim that our men or ships were instrumental in turning the tide of any one battle or enemy engagement. But the claim is justly made that the Survey helped speed the movement of men and materiel, that it was instrumental in improving the efficiency of putting ordnance on target, and that our charts, field artillery surveys, and skill in developing new instrumentation and methods saved countless American and Allied lives. Much of this work was done at the front as our officers were subjected to all the hazards of land, air, and naval warfare.

C&GS officers served as artillery surveyors, hydrographers, amphibious engineers, beach masters, hydrographers, reconnaissance surveyors for the worldwide aeronautical charting effort, instructors at service schools, and in a plethora of technical positions. In Europe the work of C&GS artillery surveyors assured the success of the devastating tactic of "time-on-target." In the Pacific, C&GS ships often operated in advance of fleet units. Of the USS PATHFINDER, a C&GS ship taken over by the Navy for the duration of the war, it was said: "The road to Tokyo was paved with PATHFINDER charts." Admiral Chester Nimitz, in praising this ship's work, referred to it as a C&GS ship, because the technical expertise was provided by C&GS officers transferred into the Navy. C&GS amphibious engineers were regimental navigators for Army engineer shore and boat regiments moving men and supplies during MacArthur's leap-frog war up New Guinea and into the Philippines.