sentences:  Her crew rescued a downed American flier during evening of 21 February and watched the U.S. Marines hoist the colors on the summit of Mount Suribachi on the 23d.On 4 March, "Signet's" crew began to understand the significance of Iwo Jima as they watched the first crippled B-29 land on its airfield.On 7 March after a little more than three weeks of sweeping, patrolling, and being harassed by enemy planes "Signet" cleared Iwo Jima for Ulithi Atoll in the Carolines.