Mark with US Army Shoulder Sleeve Insignia: 31st | #400385

The United States Army is one of the three military departments (Army, Navy and Air Force) which reports to the Department of Defense. The modern US Army has its roots in the Continental Army, which was formed on 14 June 1775. The Chemical Corps is the branch of the United States Army tasked with defending against chemical, biological, radiological, and nuclear weapons. A shoulder sleeve insignia (SSI), is an embroidered patch worn on some uniforms of the United States Army. The SSI in this image was approved for the 31st Chemical Brigade in 1919.