Complex sentence: On May 29, Yamasaki organized his remaining men for a surprise frontal attack on American positions with the goal of breaking through the American front lines and seizing American artillery batteries, which could then be turned on the rest of the American forces and their ships offshore.
Split into simpler sentences: On May 29, Yamasaki organized his remaining men for a surprise frontal attack on American positions. Yamasaki hoped to break through the enemy's front lines and seize the American artillery batteries, which would then be turned on the rest of the American forces and their ships offshore.