Complex sentence: Ichiki's assault was defeated with devastating losses for the Japanese attackers in what became known as the Battle of the Tenaru: all but 128 of the 917 men of the First Element were killed in the battle.
Split into simpler sentences: Ichiki's assault was defeated with devastating losses for the Japanese attackers in what became known as the Battle of the Tenaru. All but 128 of the 917 men of the Ichiki Regiment's First Element were killed in the battle.