Complex sentence: From German reservists had made mass attacks at Langemarck, with losses of up to 70 percent, showing that industrial war between mass armies was indecisive and that troops could only move forward over heaps of dead.
Split into simpler sentences: From German reservists had made mass attacks at Langemarck, with losses of up to 70 percent. Industrial war between mass armies was indecisive and that troops could only move forward over heaps of dead.