Complex sentence: Marion thus missed the battle, which proved to be a decisive British victory, but was able to intercept and recapture 150 Maryland prisoners, plus about 20 of their British guards, who had been en route from the battle to Charleston.
Split into simpler sentences: Marion thus missed the battle, which proved to be a decisive British victory. However, Marion was able to intercept and recapture 150 Maryland prisoners, plus about 20 of their British guards, who had been en route from the battle to Charleston.