ALBANY, N.Y. (AP) — A New York Army National Guard unit that traces its lineage to the U.S. entry into the First World War is marking a century as a fighting force.

The 42nd Infantry Division was officially formed on Aug. 5, 1917, as the United States ramped up its small regular Army with units from state-run National Guard organizations. The division's first soldiers started reporting for duty two weeks later at Camp Mills outside Garden City on Long Island.

New York and more than two dozen other states contributed troops to the 42nd, which was dubbed the Rainbow Division after then-Maj. Douglas MacArthur said the unit would stretch across the nation "like a rainbow."

Part of the New York Army National Guard since 1947, the Rainbow Division is based in Troy.

More From WIBX 950