Complex sentence: Napoleon had attempted to speedily catch the British and force them to fight and he led the French army 200 miles over 10 days in forced marches in spite of winter blizzard conditions reaching Astorga on 1 January with 80,000 men.
Split into simpler sentences: Napoleon had attempted to speedily catch the British and force them to fight. He led the French army 200 miles over 10 days by forced marches and in spite of winter blizzard conditions reached Astorga on 1 January with 80,000 men.