Complex sentence: As the first four waves of American soldiers assaukted the beach they were fired upon by the Japanese and when Wai arrived on teh beach he found soldiers leaderless, disorganized, and pinned down on the open beach.
Split into simpler sentences: As the first four waves of American soldiers assaulted the beach they were fired upon by the Japanese. When Wai arrived on the beach he found the soldiers there to be leaderless, disorganized, and pinned down on the open beach.