[1] Banér was the son of Gustaf Banér who was one of the noblemen executed in 1600 at the Linköping Bloodbath, and Kristina Sture, daughter of Svante Stensson Sture.

[4] From 1622 to 1624, Banér was governor of Estonia and in 1625 he was made a member of the Privy Council.

[5] Banér served under Axel Oxenstierna and acted as Oxenstierna's deputy when the latter assisted Gustavus Adolphus in Germany during the Thirty Years' War.

Oxenstierna was however not entirely satisfied with Banér, who was often ill and suffered from bouts of melancholia,[4] and did not act with sufficient force to please his superiors.

[1][2] On 20 June 1644, Banér was suddenly taken ill with a fever, and he died three weeks later, on 13 July.