During the second world war, Germany's ports came under heavy attack from marauding Patrol Boats. German Lighters or powered barges were pretty much defenseless against them. In an attempt the defend them, guns were mounted for self defense. But the ultimate version was this Flak Lighter armed to the teeth with two 88 mm guns, two quad 20 mm guns, two single 20 mm guns and one single 37 mm gun. These Gunboat lighters were used as escorts for their less heavily armed cousins
(http://i124.photobucket.com/albums/p8/DickyD_photos/636772.jpg)