Complex sentence: Harold had spent mid- 1066 on the south coast with a large army and fleet waiting for William to invade, but the bulk of his forces were militia who needed to harvest their crops, so on 8 September Harold dismissed both the militia and the fleet.
Split into simpler sentences: Harold had spent mid- 1066 on the south coast with a large army and fleet waiting for William to invade. The bulk of his forces were militia who needed to harvest their crops, so on 8 September Harold dismissed both the militia and the fleet.