Dreadnoughts could bombard shore targets, but doing so put them at considerable risk from torpedo boats, mines and submarines. This was a risk British admirals were unwilling to take with their dreadnoughts, as they were far more useful for countering their German counterparts. Instead, monitors, ships built specifically for coastal bombardment, were used, along with a few older pre-dreadnought battleships. I've covered the operations of the RN's monitors in Belgium here, as well as the use of naval bombardments at Gallipoli here. I've also covered the Royal Navy's use of seaplanes to attack targets along the German coast. The German navy, meanwhile, could not effectively bombard Entente positions in Belgium and Northern France because the Allies dominated the English Channel and south-western North Sea. German naval activity in this area was limited to a few destroyer raids on Allied shipping.

The region along the Belgian coast where the Allied and German lines faced off against each other was not capable of supporting an offensive that could exploit the advantages that any naval gun fire could offer. During the first months of the war, the Belgian army, withdrawing westward as the Germans advanced through Belgium, opened the locks at Veurne-Ambacht, allowing seawater to flood the Yser River and the plains north of Ypres, thus preventing the Germans advancing further and threatening the flank of the British positions around Ypres. This was a particularly heroic things to do as salt water and agriculture don't mix very well. Because of the flooding, the area became impassable except for roads that lay above the water level. This severely restricted the potential avenues of advance and denied the area to both the Germans and the Allies in regards to operational use throughout the war.