L990 monitor, a floating shitty technical.
Just after the end of WWII, France had to be able to patrol the Rhine river once again but most available boats were either unusable or outdated, with very few remaining river-worthy. Thus the French took a Landing Craft and stuck a M4A2 on it and called it a river monitor. These boats served until 1955, even if proper patrol boats were built in 1946.