When did the Army go from blue uniforms to O.D. (Olive Drab) uniforms?
The Army made the uniform change in 1904, just about the same time they adopted the Springfield Model 1906 .30-06 rifle. I might add, the First U.S. Voluntary Cavalry, Teddy Roosevelt’s Rough Riders, wore tan canvas trousers to go with their blue shirts in the 1898 Spanish-American War.