At the start of the month Germany launched an escalated U-boat campaign, allowing the submarines to attack civilian ships without stopping to search them for contraband or give their occupants a chance to abandon ship. German leaders are aware that this risks war with the United States, but they have been persuaded by the memorandum of Admiral Holtzendorff, which projected that unrestricted submarine warfare will starve Britain into submission in a matter of months.
This month U-boats have sunk just under 500,000 tons of enemy shipping, an increase of 50% on the previous month. The gains are impressive, though they are still short of what the navy had projected as necessary to defeat the British. It is also not entirely clear how much of the increase is due to the new tactics. The U-boats had started sailing through the English Channel late in January, which meant they had more time to spend on patrol. However German leaders remain confident. The U-boat campaign in the early part of this month had been somewhat restrained, to allow neutral shipping to escape the war zone around the British Isles. There will be no such restraint next month. The submarines will be completely off the leash and Britain will soon be on her knees.