Complex sentence: Belgian military planning was based on an assumption, that other powers would eject an invader but the likelihood of a German invasion did not lead to France and Britain being seen as allies or for the Belgian government intending to do more than protect its independence.
Split into simpler sentences: Belgian military planning was based on an assumption that other powers would eject an invader. The likelihood of a German invasion did not lead to France and Britain being seen as allies or for the Belgian government to intend to do more than protect its independence.