Prince Christopher actively participated in the war for reconquest of Denmark which his father had initiated. Scania, which at the time was a Swedish territory, was returned to Denmark in 1360. The German Hanseatic League responded by sending a large fleet into Øresund in the spring of 1362. The Germans landed at Helsingborg and began to besiege the castle with (among other things) 16 catapults. Through a surprise attack from the sea (Battle of Helsingborg (1362)) King Valdemar managed to win a crushing victory. After his victory at Helsingborg, King Valdemar sought to resolve the conflict through diplomacy. He managed to marry his daughter Margaret to Haakon VI of Norway, the son of Magnus IV of Sweden.
Christopher was injured in the naval battle. German chronicles are not clear about what weapon inflicted the prince's mortal wound, but according to Swedish Henrik Smith's chronicle from the early 1500s Christopher was hit by a rock while fighting at sea. According to Nordisk familjebok, Christopher was shot in the head with a rock and subsequently suffered from a mental disorder. The prince died from illness the following year in Copenhagen, two months after the marriage of his sister Margaret and the death of Swedish Queen Blanche, and was subsequently buried in Roskilde Cathedral. Although his death is often attributed to his war wounds it is unknown to what extent his injuries actually contributed to the illness.