All three cruisers participated in Operation Weserübung. Königsberg and Köln helped deliver about 1,900 troops to Bergen, while Karlsruhe and three torpedo boats carried roughly 1,100 to Kristiansand. The ships could embark substantial forces because a minelayer's design accepted space and weight that a conventional cruiser might not. This is a useful example of a nominally awkward capability becoming operationally valuable in an amphibious campaign.
Chapter · 26:41-28:18
Operation Weserübung: minelayers with troop capacity
During the invasion of Norway, the class's spare volume for mines also made the ships valuable troop carriers for Bergen and Kristiansand.