Complex sentence: Thousands of American and Filipino soldiers died of their wounds on the infamous Bataan Death March or were brutally murdered by Japanese troops (many of whom were actually from the Japanese colony of Korea) when they could not keep up with the pace.
Split into simpler sentences: Thousands of American and Filipino soldiers died of their wounds on the infamous Bataan Death March. Others were brutally murdered by Japanese troops (many of whom were actually from the Japanese colony of Korea) when they could not keep up with the pace.