Episode spoilers.
On Okinawa, Sledge is an experienced Marine with little patience for replacements or Japanese prisoners. Rain turns the ground to mud, and the men carry their exhaustion into every new position. Snafu and Leyden bully a replacement, Peck, who is already struggling to cope. When Sledge shoves a prisoner repeatedly, Mac intervenes and warns him that attacking captives again could bring a court-martial. Sledge's anger now makes trouble inside his own unit as well as across the lines.
The fighting brings civilians directly into the Marines' path. A woman and baby become part of a Japanese attack involving concealed explosives, and American fire also hits the Marines. Peck breaks down after a disastrous mistake. Sledge grows harsher, killing a wounded Japanese soldier despite an order to stop. The men continue through mud and ruined buildings, where the distinction between clearing enemy positions and finding people who need help becomes painfully difficult to act upon.
Inside a damaged house, Sledge and Snafu find a surviving baby and a dying woman. After the child is taken away, the woman asks Sledge to kill her. He cannot do it and holds her while she dies instead. Outside, he spares an unarmed Japanese youth and angrily confronts the Marine who shoots him. Later, under clear skies, the men hear that an American bomb has destroyed a Japanese city. They receive the news quietly as aircraft pass overhead.