In the Battle of Lützen (1632), on 6 November 1632, Gustavus Adolphus died. This meant that Oxenstierna became supreme commander of the Swedish troops in Germany, although he let his subordinate generals be responsible for the military operations on a lower level. He moved his headquarters to Mainz, which in practice became the new Swedish capital. Oxenstierna was now absolute ruler of the significant area that the Swedish army had conquered in Germany. He was offered the position as prince-elector of Mainz, but, after serious considerations, the offer was turned down.