For the Luzon invasion in 1945, I found this troop list for US I Corps. I wanted to highlight the support troops found there and contrast the Corps organization in the Pacific with a US Corps in Europe. Information about the US XIX Corps is available here: http://www.xixcorps.nl/ By design there was not a fixed Corps organization but rather units were attached from Army for the expected operations. For this reason there were significant differences in the composition of a Corps in Europe versus the Pacific. In Europe a Corps could consist of three or four divisions, up to four field artillery groups, an anti-aircraft artillery group, one or two engineer groups plus supporting ordnance, quartermaster and medical units. On Luzon, a campaign most similar to Europe, I Corps had up to four divisions, one field artillery group, an anti-aircraft artillery group, an engineer group plus supporting ordnance, quartermaster and medical units. Actual Corps troops consisted of the Corps Headquarters and Headquarters Company and the Corps Artillery Headquarters and Headquarters Battery. A Signal battalion seemed to be required but still may not have been assigned but rather attached. I have noticed I Corps is often referred to as "i corps" (sounds like "eye core") -- "One Corps" does seem awkward otherwise "Two Corps", "Three Corps", ... works for me. Units cited below are often repeated where they were split-up to support different units or had different assembly areas. I tried to provide the full title of as many units I could identify. The proper title and function of others completely evaded me. Feel free to post factual information on these units. Common abbreviations Engr - Engineer Sig - Signal FA - Field Artillery Ord - Ordnance AAA - Anti-aircraft Artillery Med - Medical Cml - Chemical QM - Quartermaster MP - Military Police Arty - Artillery Hq - Headquarters Det - Detachment Sec - Section Plat - Platoon Co - Company Btry - Battery Bn - Battalion Gp - Group The compostion of I Corps changed through the campaign. Some of the changes to the field artillery and engineers is reflected in these excerpts.