The Rhein class of ironclad riverine monitors (Flußkanonenboote) were a pair of ships built by the German Imperial Navy in the aftermath of the Franco-Prussian War.

The class comprised two ships, Rhein and Mosel; both were built by the AG Weser shipyard in Bremen, in 1872–1874.

The ships were intended to protect the German border with France in the event of a conflict, but had short service lives, as war did not come.

The German Navy decided that two armored gunboats were necessary, and awarded the contract to AG Weser to design and build the vessels.

The design staff based their work on a pair of Austro-Hungarian monitors, Leitha and Maros, that had been recently built for service on the Danube.

The ships were designed to partially flood for combat, which would submerge the hull so only the upper casemate and gun turret would be above water.

[2] The ships were powered by two horizontal 2-cylinder single-expansion marine steam engines; these drove a pair of 3-bladed screw propellers 0.95 m (3 ft 1 in) in diameter.

They spent the first year of their career at Rheinhausen, and in April 1875 both vessels embarked on a test cruise to Strassburg.

[6] By the time the two monitors entered service, the prospect of a French attack had decreased, prompting the Navy to question the usefulness of retaining the vessels.