A large portion of the regiment was made up of German mercenaries, who were a common phenomenon on both sides.

The regiment's name is derived from the blue colored uniforms worn by the soldiers.

[1] The regiment was raised around 1624 during the Polish–Swedish War of 1621–25,[2] originally recruited from Swedish provinces.

Following the landing of Gustavus Adolphus and his army in Pomerania, new recruits came from local German inhabitants to fill the ranks.

Battle of Lützen in particular, where it is referred to as the "Old Blue" regiment, though this name was official from 1634 only, was disastrous to the regiment as it lost more than half of its veteran soldiers from the recurring attacks of the Imperial cavalry and the heavy enemy volleys.