During WW II crawler tractor / bulldozers were used by the U.S. military for combat construction in Europe, Asia, the Pacific, literally all over the world. They also served as prime movers for artillery, and for a multitude of other tasks. The crawler tractors had unsurpassed capability to move and tow in the muddy jungles of the Pacific islands which made them especially prized by SeaBees, Marine Corps and Army units in the Pacific Theater. When equipped with a bulldozer blade, they could level ground for roads and airfields as well as clear debris, construct fortifications and much more.
Tractor / Bulldozers were produced in great variety, from small, air transportable units that flew with airborne engineers to hulking brutes used to move the heaviest field artillery under adverse conditions.
According to TM 9-2800 (1 September 1943) War Department tractor / bulldozers were standardized under three general nomenclature groupings, with several commercially available models in each group, as follows:
Thanks to az_mike_miller for recommending "Bulldozing the Way: New Guinea to Japan."
Clarkair Crawler CA1. Air transportable tractor/dozer with Braden winch. Developed by Clark, and approx. 1100 built by Clark Equipment Co. and American Machine and Metals Inc. for US Army during WW II. Thanks to Stephen Sarkany for corrected information.