Complex sentence: Around 8:00 am, another force appeared, and the redcoats abandoned their breakfast to man their position again; however the force turned out to be the vanguard of Lord Chelmsford's relief column.
Split into simpler sentences: Around 8:00 am, another force appeared, and the defenders abandoned their breakfast to man their position again. However the force turned out to be the vanguard of Lord Chelmsford's relief column.