Complex sentence: The mission was deemed a success though many of the people who were supposed to be rescued were killed during the bombing they were due to be killed anyway and many more escaped including some leading figures in the fight against Germany.
Split into simpler sentences: The mission was deemed a success though many of the people who were supposed to be rescued were killed during the bombing. Some argue they were due to be killed anyway, and many more escaped including some leading figures in the fight against Germany.