A restless Basilone is transferred to the 5th Marine Division where he trains Marines for combat. There he meets and marries Sgt Lena Riggi. Called to lead his traniees into battle on Iwo Jima, Basilone is killed by shrapnel from a Japanese mortar shell.
Sledge and Leckie land with the 1st Marine Division at Peleliu. Sledge leaves America to join the forces in the south Pacific and has a harrowing introduction to combat when he participates in the assault on Peleliu. Back home, Basilone promotes the war bonds programme.
The Marines move to capture Peleliu's vital airfield. During battle, Leckie is wounded by a blast concussion while trying to relay a message to the corpsman and evacuated to a hospital ship. Sledge realises he is still far from accustomed to the brutal realities of war.
Sledge and the 5th Marines move into Peleliu's Bloody Nose Ridge to face the Japanese. Andrew "Ack-Ack" Haldane is killed by a Japanese sniper while assessing Hill 140. Back home, Basilone becomes disillusioned with selling war bonds and longs to rejoin his comrades.
Sledge and the 1st Marines land at Okinawa. Sledge, now a seasoned veteran, becomes more cynical and no longer shows any compassion for the Japanese. As he and others prepare to return home, they hear of a "new bomb" that vaporised an entire city in the blink of an eye.