Like many clothing items, the t-shirt has competing histories. Both the British and US Navies claim to have invented it. Certainly by 1913, the US Navy added a buttonless wool undershirt to its uniform. Sailors wore this plain undershirt during messy tasks, instead of their smart uniform.

During World War 1, cotton shirts became popular, perhaps borrowed from the French military. By World War 2, the cotton t-shirt was standard in the US military. It had become a symbol of masculinity and strength, whilst still being comfortable.