In the First World War the Royal Navy and Imperial German Navy were two of the largest European navies. After the naval race preceding the war, both countries had expanded their navies with new Dreadnought-class battleships. As such, they were the warships expected to win the war at sea. However, there were relatively few notable surface fleet battles in this war.
Undoubtedly, battleships were still a key part of naval tactics. For example, during the Gallipoli Campaign in 1915 the operation was supposed to be won with French and British battleship bombardments at Turkish positions along the Dardanelles. However, if anything this campaign highlighted the shortcomings of such tactics as their dreadnoughts ran into sea mines and a number were lost in action. When it became clear that the naval bombardment had been ineffective, the Entente began land operations in Gallipoli with troop landings.
While the battleships were the largest warships, developments in naval warfare provided new scope for tactics. Among these were German U-boats, otherwise submarines, which the Germans added to their navy. These underwater vessels had the obvious advantage of being almost entirely invincible, except when they had to resurface. While early submarines could not remain underwater so long, as aerial reconnaissance was very limited at the time it was not so easy to find U-boats.
So U-boats became a key part of German naval strategy. As the Royal Navy was larger than the Imperial German Navy, surface fleet battles with Britain's fleets were not especially welcome by those within the German High Command. Instead, with the submarine Germany could target and sink British merchant ship supplies. Submarine warfare began in the early stages of the war, and in 1915 U-boats even targeted large ocean liners such as the Lusitania that carried some armaments and munitions along with their passengers.
One notable exception to U-boat tactics was the Battle of Jutland. Economic blockade was also a big part of the Royal Navy's tactics, and with its larger surface fleet they blockaded German supplies. By 1916 this strategy had become more effective, so the Germans were ready to mobilize their surface warships for battle with Britain's Grand Fleet. The plan to defeat the blockade was to trap and wipe out much of the Grand Fleet with two fleets of German warships.
As such, the Grand Fleet met the Imperial German Navy's fleets off the coast of Jutland. The battle involved many of the larger dreadnoughts of the two navies, and it was Germany's that were actually more effective. A greater tonnage of British ships was lost during the battle, but the Germans still withdrew and did not wipe out the Grand Fleet.
As Britain's economic blockade continued after the Battle of Jutland, U-boat tactics may have seemed the only feasible naval strategy. A renewed U-boat Campaign began in 1917 that the Germans expected to defeat Britain by targeting a greater tonnage of merchant ships. The campaign began well, and merchant ship losses increased during the early months.
This might have been a period when Britain came close to losing the war. If the losses were not cut, then food shortages in the U.K. could have become prevalent, leaving little option but to sue for peace. Only when the Royal Navy turned to, and expanded, convoy tactics would the shortages decrease. Providing more destroyer and cruiser escorts gradually began to decrease merchant shipping losses during the campaign.
In addition to this, Britain also began to target German U-boat bases. By taking out their bases, the British could then further reduce the number of U-boats. Among these submarine raids was the Zeebrugge Raid in 1918.
Overall, economic blockades were the most effective naval tactics of this war. Britain and Germany had different tactics for blockade, but nonetheless both were effective. Only surface fleet convoys could cut Britain's losses during 1917. The battleships had not been so effective during campaigns such as Gallipoli, and neither side could win a decisive victory at the Battle of Jutland with their armada of dreadnoughts. Consequently, battleships would become more obsolete during the interwar period as navies constructed submarines and aircraft carriers in increasing numbers.