Apart from specially built coastal defence ships, some navies used various obsolescent ships in this role. The Royal Navy deployed four s as guardships in the Humber at the start of the First World War. Similarly, the U.S. Navy redesignated the and classes as "Coast Defense Battleships" in 1919. Such ships tended to be near the end of their service lives and while generally considered no longer fit for front-line service, they were still powerful enough for defensive duties in reserve situations.
