expression, godan verb (-su)
die on the battlefield; leave one's corpse exposed
Literary or dramatic expression for dying in battle, often with a sense of honor or tragedy. The image is of a corpse left exposed on the field.
彼は祖国のために屍をさらした。
He died on the battlefield for his homeland.
Variant using 晒す, which emphasizes exposure or bleaching.
Neutral, factual term for dying in battle. 屍をさらす is more literary and emphasizes the exposed corpse.
Compound of 屍 (corpse) + を + さらす (expose). The literal meaning is 'to expose one's corpse', idiomatically used for dying on the battlefield.