The regiment was shipped to Germany and arrived at Wolgast in June 1631 to participate in the Thirty Years' War. Its first major battle was the Battle of Breitenfeld on 17 September that same year, where it stood in the first line. It also stood in the first line as part of the Swedish Brigade at the Battle of Lützen the next year, a battle which caused heavy casualties to the regiment. The regiment's "creator", Gustav II Adolf, was killed in a cavalry charge trying to ease the pressure on the Dalarna Regiment's part of the front. The regiment returned to Sweden to replenish shortly after and remained at home until 1638, when one of the regiment's two battalions was sent as garrison to Stettin. The Dalarna Regiment was one of the original 20 Swedish infantry regiments mentioned in the Swedish constitution of 1634. Carl Gustaf Wrangel was the commander from 1639 on. The second battalion was sent to Germany in 1642, and the whole regiment fought at the Battle of Leipzig that year, only to return to Sweden again the following year. They were present during the siege of Landskrona in 1644 during the short Torstenson War.