Complex sentence: Edward and his brothers then defeated Warwick at the Battle of Barnet, and with Warwick dead he eliminated the remaining Lancastrian resistance at the Battle of Tewkesbury in 1471.
Split into simpler sentences: Edward and his brothers then defeated Warwick at the Battle of Barnet. With Warwick dead, Edward eliminated the remaining Lancastrian resistance at the Battle of Tewkesbury in 1471.