He is often regarded as one of the greatest military commanders in modern history, with use of an early form of combined arms. His most notable military victory was the Battle of Breitenfeld (1631). With his resources, logistics, and support, Gustavus Adolphus was positioned to become a major European leader, but he was killed a year later at the Battle of Lützen (1632). He was assisted in his efforts by Count Axel Oxenstierna, the Lord High Chancellor of Sweden, who also acted as regent after his death.