Something as simple as a T-shirt has a military connection. And this year, it celebrates its 100th birthday. In 1913, the U.S. Navy was the first military branch to issue the T-shirt to be worn under uniforms. By WWII, it became standard issue for both the Navy and the Army. Labeled as “underclothing,” it eventually became acceptable for soldiers to remove their dress shirt while working in hot climates, wearing nothing but their uniform pants and a T-shirt. While the public didn’t love that idea at first, more and more people embraced T-shirts when new designs and colors emerged in…