Complex sentence: Refusing to risk everything in a major battle, Philip retreated, only to have his rear guard caught at Fréteval on 3 July, which turned into a general encounter where Philip barely managed to avoid capture as his army was put to flight.
Split into simpler sentences: Refusing to risk everything in a major battle, Philip retreated, only to have his rear guard caught at Fréteval on 3 July. This turned into a general encounter in which Philip barely managed to avoid capture as his army was put to flight.