Complex sentence: After the failure to capture the city of Petersburg the previous week, Lt. Gen. Ulysses S. Grant decided on a siege and the Union army entrenched east of the city, running from near the Jerusalem Plank Road in the south to Bermuda Hundred in the north.
Split into simpler sentences: After the failure to capture Petersburg the previous week, Lt. Gen. Ulysses S. Grant decided on a siege. His Union army entrenched east of the city, running from near the Jerusalem Plank Road in the south to Bermuda Hundred in the north.