Great Northern War
Charles XII left the Ottoman Empire in 1714 and went to Stralsund in Pomerania which was owned by Sweden at the time but was under siege.  Charles escaped back to Sweden just before the people in Stralsund surrendered. Then he invaded Norway (which was owned by Denmark at the time.) and was shot and killed there. With their king gone, the Swedish soldiers left Norway and went back to Sweden. On the way back many soldiers died.