WW I submarine warfare

The submarine was conceived at the end of the 19th century. But Tirpitz’s concern for effectiveness led him to wait until the fabrication of more dependable diesel motors and of the gyrocompass before engaging in mass production of long range U-boats. When in 1904 Tirpitz recruited engineers to work on U-Boats (Unterseeboots) Krupp was quick to spot the prospect of a domestic construction monopoly, and his Germaniawerft built 101 U-boats by the end of WWI.  Yet, at the unforeseen outset of WWI, the German Navy had fewer, albeit technically superior submarines than its competitors.[1]

By 1909 the submarine had been recognized as the most effective adversary of the fast battleship, but there were controversies about its strategic use. Initially, the U-boat was conceived as a weapon against battle ships. Tirpitz soon argued that it should be used also for economic warfare. He rightly suspected Britain’s plan for a “hunger blockade” of Germany employing submarines against foreign merchant ships. While the Kaiser and the German chancellor worried about the international implications of using submarines to attack merchant vessels, Tirpitz was convinced their deployment, albeit problematic, was inevitable.

The international law had been drawn up for enemy surface warships before the invention of the submarine. While warships were supposed to follow the rule of ‘visit and search’,[2] unrestricted submarine warfare (USW) meant the sinking without warning of merchant ships navigating in a declared blockade zone, whether belligerent or neutral, armed or unarmed. This was illegal, an infringement against the principle of the right of the neutrals to freedom of the seas.  There were fears that the sinking of neutral, particularly American ships on the way to Britain would provoke hostile reactions, and even a declaration of war. Although they understood German arguments that the British blockade violated naval agreements, the Americans did not press London to comply with international law, whereas they refused to accept unrestricted submarine warfare as a legitimate German countermeasure.

These were the very reasons why the Kaiser and the Chancellor had adopted a back-and- forth policy on submarine use. But it laid bare the lack of German naval strategy. Tirpitz alone had one. England and Germany had the same aim: to stop food from reaching the other side with reasonable respect for neutral countries and human life. If in order to achieve this aim, England did not respect international law via a food embargo, Germany had to do the same via unrestricted submarine warfare.

When in the early winter 1914/15 the use of U-Boats in the trade war was first discussed, Tirpitz supported unrestricted submarine warfare (USW) rightly suspecting the Americans to be unprepared to intervene. Aware of the German submarine shortage at the beginning of the war, Tirpitz indicated that it was impossible to blockade all English ports, and recommended to concentrate submarine activity at the mouth of the Thames River. At first, the Kaiser refused and German government did nothing. Tirpitz therefore asked the Kaiser to be allowed to submit his resignation, which was refused. However, when at the end of 1914 England declared the whole North Sea and the Norwegian Sea as war zone, the German government did actually launch USW, but instead of concentrating on the mouth of the River Thames, announced that it considered ‘all waters around Great Britain and Ireland including the whole English Channel’ as a war zone, and that, ‘from 18 February 1915 all enemy merchant vessels in that area will be destroyed.’ This was a serious mistake due to the shortage of German submarines.

On 20 January 1916, considering that an intervention by the Americans had become inevitable, Tirpitz sent to the Kaiser a memorandum advising a return to limitless U-Boat war against all ships under enemy flag…He estimated that England had lost seven million tons of merchant ships, with less than 12 million tons remaining, making the U-boat a decisive war weapon to give Britain a decisive blow, before the Americans could come to rescue it. But his advice was ignored again until it was acted upon only in January 1917.

The German people had been suffering a growing number of casualties due to food shortages. These would amount to well over three quarters of a million people between 1914 and 1919, when the British “hunger” embargo was lifted. As the Battle of Jutland had proved inadequate to lift the British trade embargo, in January 1917 the Kaiser and his Chancellor re-launched a policy of USW against all vessels in a “war zone” around Great Britain. This seemed a last bid to starve Britain in turn and win the war. Although the rationale against such a move had not changed, the Kaiser felt he had no other choice.

Tirpitz remained convinced until the end of his life that delayed submarine war action caused Germany’s defeat; starting targeted USW in early summer 1915, before additional 30 German U-Boats had become available, if well carried through, and even USW in January 1916 with all submarines that had by then become available, would have, in his view,  avoided Versailles.

In April 1917, a German U-Boat sunk the passenger ship Lusitania, an auxiliary cruiser of the Royal Navy loaded with contraband weapons. Some 1,200 passengers drowned, including about one hundred Americans. Although German officials had warned Americans not to board the ship, there was outrage across the Atlantic. After that, Wilhelm backed off ordering all German submarines to spare neutral vessels, and introduced even stricter limitations after the sinking of another foreign vessel. This jeopardized the effectiveness of the new weapon. Soon after that, Tirpitz requested once more his resignation. Wilhelm accepted it on 15 March 1916. Wilhelm then ordered to stop sinking any vessel (without prior warning) thereby halting German submarine operations altogether.

German policy U turns and inconsistencies notwithstanding, initially things went well for the German navy. In March to May 1915 it sank 115 British ships with more than 600,000 tons, losing just five U-boats, even though it could count only on thirty-seven submarines of all descriptions of which twenty long-range boats, with an average of no more than six of them daily at sea. While the destroyed tonnage corresponded to early German projections, the figures dwindled when the Royal Navy organized merchant traffic in convoys, which were increasingly escorted by ships of the American navy.

The news of Tirpitz’s dismissal on 19 March 1916 triggered a storm of support for him…and only censorship muted the national outcry in the press. Tirpitz’s dismissal was a milestone in the disaffection of the German right, both old and new, from the Kaiser and – though less conspicuously – the monarchic system.


[1]  See: RS, op.cit.p.26. At the outset of the war the Germans had only 28 ready U-Boats, the English double as many with 54. But 37 of the English boats could be employed only for ‘local defense’ or for action in the Channel (where there were no German ships!). Admiral Galster, who in 1907 had criticized Tirpitz for neglecting the U-Boat weapon, recognized after WWI that this had spared him the set backs experienced by others (cited by FUW, op.cit. p.335)

[2]  “The rules of merchant warfare provided that warship stop the commercial vessel, search it for counter band, and sink it only after rescuing the crew. Submarines could hardly abide by these rules (it could be destroyed by gunfire if surfaced and could not accommodate the vessel’s crew). The submarine was most effective if it attacked by surprise, but then its commander could not always recognize the type and nationality of the ship torpedoed.” (RS, p. 25)