Germany’s U-boats could perhaps knock Britain out of the war by strangling its trade, but only if they are permitted to torpedo ships at will. However this kind of gloves-off U-boat warfare risks bringing the United States of America into the war against Germany.
Germany’s leaders are divided on whether the gains from an escalated U-boat campaign offset the risks of US entry into the conflict. Falkenhayn, the army’s chief of staff, is in favour of letting the U-boats off the leash. He sees Britain as Germany’s main enemy and attacks on British trade as a key weapon to force it out of the war. Chancellor Bethmann Hollweg however thinks that Germany has quite enough enemies already and can do without adding the United States to their ranks; he is therefore adamantly opposed to unrestricted U-boat warfare.
The ultimate decision-maker is the supreme warlord, Kaiser Wilhelm himself. Yesterday he met with Falkenhayn and accepted the arguments in favour of letting loose the submarines. But today he meets James Gerard, the US ambassador. Gerard is protesting about the recent sinking of the Sussex and other incidents. The Kaiser initially counters with complaints about US acquiescence to the Allied blockade of Germany, but he backs down when faced with the prospect of a rupture with the United States. The Kaiser promises Gerard that German submarines will refrain from indiscriminate attacks on merchant shipping.
Germany’s leaders (World War I Today)