February 1st, 1915

- Admiral Hugo von Pohl, Chief of the German Naval Staff, had interpreted the British declaration of November 1914 that the entire North Sea was a war zone as an effort to deter neutrals from sailing to Germany, and in particular to starve Germany via the interruption of food imports.  In response, Pohl had become a convert to the idea that Germany should use its own submarine force to attack merchant shipping bound for Britain.  Today in a meeting with Chancellor Bethmann-Hollweg, he advocates a shift in strategy to embrace what is known as unrestricted submarine warfare.

According to international maritime law, a specific procedure was to be following when a warship intercepts merchant shipping.  First, the attacker would have to halt the merchant ship either by signals or a warning shot.  Second, sailors from the warship would have to board the merchant ship to ascertain its cargo and nationality.  Third, if the merchant ship belonged to the enemy, provision had to be made for the safe evacuation of the crew and any passengers.  Only at this point could the warship actually sink the merchant ship.  These rules were drafted in the age of the sailing ship, when the attacker would be a fast light warship that nevertheless would have space to take the merchant crew aboard.  On the other hand, these rules were manifestly impossible for submarines to follow if they were to achieve any success.  Submarines relied on stealth and surprise, advantages which would have to be surrendered if they had to signal a merchant ship to stop first.  Second, a submarine is at its most vulnerable when on the surface, making it potentially disastrous to stop and wait while sailors board the merchant ship to inspect it.  Finally, the size of the submarine left no room whatsoever to take on the crew of a sunk merchant ship.  To operate in line with contemporary maritime law would greatly reduce the value of a submarine as a weapon against enemy shipping, and hence was referred to as restricted submarine warfare.

At the outset of the war the general expectation on all sides was that submarines would still adhere to maritime law, and indeed German submarines had done so for the first six months of the conflict.  However, given the tightening British naval blockade, Pohl is not the only German admiral to advocate that the U-Boat force stop adhering to international law in order to reach their full potency as a weapon against British trade, which is referred to as unrestricted submarine warfare.  To its advocates, this policy promised a means to strike back at the one main enemy that remained frustratingly beyond the reach of the German army or the High Seas Fleet.  Moreover, given British reliance on imports, especially of food, unrestricted submarine warfare had the potential to cripple the British economy, and perhaps even force its surrender.

Unrestricted submarine warfare was not without its difficulties.  For one, it would be another action that would tarnish the image of Germany elsewhere, and of particular concern was the potential for neutral merchant ships to be sunk by accident, which might lead to additional countries entering the war on the side of the Entente.  The biggest neutral, of course, is the United States, and the fear expressed by some is that adopting unrestricted submarine warfare may push it closer to the British.  Further, there could easily be incidents where passenger liners are mistaken for merchant ships, and the sinking of the former could lead to substantial civilian casualties and international outrage.  These reasons are why not only the German Chancellor but the Kaiser himself have refused to date to endorse the implementation of unrestricted submarine warfare.

Pohl, however, has persisted in his advocacy, and today attempts to assuage the Chancellor's concerns.  He argues that if Germany declares a war zone around Britain, it will scare away neutral shipping, which means that there will be neutral merchants in the area for U-Boats to sink by accident.  In additional, Pohl declares that submarine captains are able to distinguish between enemy and neutral ships, and between passenger liners and merchant ships.  Given these assurances, Bethmann-Hollweg consents to unrestricted submarine warfare.