Flames of War Stars & Stripes: Intelligence Handbook on US Armored and Infantry Forces By Phil Yates

The badge of the Is1 Infantry Division was a large red ' 1' on a green background, giving the Division its nickname— 'Big Red One*. The Division consisted of three infantry regiments, the 16th 18th and 26th. The 16th and 18th Infantry Regiments had a long history having fought in the American Civil War. the Spanish American War. and the First World War. The history of the 26,h Infantry Regiment was nearly as illustrious. It was formed in 1901 and had fought in the Philippines and in the First World War. where these regiments First came together as a permanent division.
When Germany invaded Poland in 1939 and sparked the Second World War. the Is1 Infantry Division was undermanned and scattered across a variety of barracks. It was hurriedly brought up to strength along with the three other divisions then in existence (Germany had over a hundred divisions ready for battle!) The National Guard was called up for federal service and new divisions were authorised as fast as troops could be trained to man them.
In 1942 the Division was sent to England, where it trained for the invasion of Europe. However, in November 1942. the Big Red 1 was sent to North Africa instead.