Upon his recovery, Rosecrans was promoted to the rank of colonel and appointed quartermaster of I Marine Amphibious Corps under Major General Clayton Barney Vogel for a brief period before he was ordered to take command of newly activated 17th Marine Regiment (Engineer) on January 21, 1943. He led this regiment during the Battle of Cape Gloucester and was relieved by Colonel Francis I. Fenton on February 19, 1944.