Why is the Colonel Called "Kernal"?
The Origin of the Ranks and Rank Insignia Now Used by the United States Armed Forces

Enlisted Ranks:

Corporal

Corporals often command squads in our Army and Marine Corps. That was also their job in the Fifteenth Century Italian armies. An important tactical formation was the squadra, or square, headed by a reliable veteran called the capo de'squadra or head of the square although some squadra members might have looked on their leader as the "squarehead." The title seems to have changed to caporale by the Sixteenth Century and meant the leader of a small body of soldiers. The French picked up the term in about the Sixteenth Century and pronounced it in various ways, one of them being corporal, which indicates a mixing with the Latin word corpus or French corps, both of which meant body. The British adopted corporal in the Seventeenth or Eighteenth Century and it has been a part of their army ever since. The British gave the Corporal his two stripes when they started using chevrons in 1803.