He is famous for his flanking movement to surprise King Christian I of Denmark's army at the Battle of Brunkeberg in 1471.

Nils joined Sten's armies in preparation to defend Sweden.

Nils Sture traveled to central Sweden to recruit more Peasant Militia and Provincial Knights as Sten was doing.

Sten was to launch the juggernaut at the Danish front, and Nils was to attack using a flanking movement.

The three Swedish Generals won against the Danish, but Posse was mortally wounded and died in Stockholm.