The roles of the World War I monitors and the 19th century monitors were very different.
The World War I Shore Bombardment Monitors were designed as Coastal Offence ships. Often towed to where required at places such as Gallipolli or the Belgian coast, they then bombarded the enemy. Apart from three exceptions, these "monitors" did not have the low freeboard of the 19th century monitors.
The 19th Century Low Freeboard Monitors were designed as Coastal Defence ships, where their task was to defend the home ports. Crucially these ships had a "monitor deck" also known as "low freeboard". These two terms simply mean that the lowest deck outside the ship was very close to the water.
For details on the history of the Coastal Offence Monitors see Ian Buxton's excellent book - Big Gun Monitors, Design, Construction & Operations 1914-1945, Seaforth Publishing, 2005.
The Exceptions
Brazil's inability to pay for three river monitors that she had ordered led to the three ships being acquired by the British so as to deny them to anyone else. These were true monitors with low freeboard designed for operation in Brazil's coastal waters and rivers. The success of these ships, Severn, Humber and Mersey, in stabilising the French front in the early stages of the First World War encouraged the construction of the larger Bombardment Monitors.
The Ex-Brazilian Monitors seen from the Stern Photo courtesy of George Wilkins
As well as serving off the coast of Belgium to stem the German advance in 1914, Mersey and Severn served off the coast of East Africa and sank Königsberg in 1915. Humber operated off ANZAC Beach at Gallipoli, shelling Turkish Batteries that were firing against Australian and New Zealander troops. 1918 saw Mersey, Severn and Humber reunited and sailing through the Dardenalles. Mersey then operated on the Black Sea and Danube River.
Monitor in Action - Casing Removed - Funnel Mast & Superstructure having been Re-erected -
"The transport of a monitor across the ocean to its proper home in river waters is a little romance in itself. This type of vessel of course, is not built for blue water, so all the upper works are taken down and packed snug, and the vessel is cased over with steel plates and towed on its long journey by powerful tugs. At its destination the superstructure is re-erected. "These rather abnormal fancy vessels," as Mr. Balfour told the House the other day, "have done some very good service at the Dardanelles and off Belgium, but they swallowed up the guns and gun-mountings designed for capital ships, and some were so hastily built that they have to be remodelled."
World War I Monitor under tow.
Sea Monsters that are dreaded by the Huns
How the Navy assists the Land Forces in Flanders
The Graphic, 12 October 1918
PRACTICE MAKES PERFECT - A new type of British monitor in action in support of the Allied armies, which are causing the enemy to relax the grip he has so long held on the Belgian coast.
SOMETHING LIKE A DISCHARGE - A salvo by big guns, from whose gaping mouths are belched forth dense volumes of yellow cordite smoke, red-hot gas and red-brown combustion smoke (from silk cartridge bags).
British Monitors In Action Against The Enemy's Shore Batteries: Special "Sphere" Picture.
The Sphere, 13 April 1916
The Navy's Special Craft At Work - Four Monitors Shelling The Enemy's Batteries At — The Sphere, 13 April 1916
The work of the special craft which the navy has been employing in various waters has a particular interest at the present time. Here we see four of the British monitors, each with its pair of big guns in a turret in the bow, dropping careful, well-placed shots at the enemy's batteries on shore. Each carries a sturdy tripod mast. While the gunners are engaged in their work other craft are ceaselessly guarding the squadron from undersea attack. Among these vessels are armed trawlers, whose work in the war has been most varied, important and generally accompanied with great danger, and whose crews Andiral Bacon's despatch spoke of as demonstrating the fine adaptability of the British race to sea work. A British destroyer is seen in the foreground, dashing round the squadron with a keen eye for submarines and floating mines.
