Cruiser rules

However, if it is intended to take the captured ship as a prize of war, or to destroy it, then adequate steps must be taken to ensure the safety of the crew.

Attempts to codify these rules include agreements between Great Britain and France at the end of the Crimean War which were extended internationally at the Paris Declaration Respecting Maritime Law in 1856.

[5] A new international agreement was reached in 1909, the London Declaration concerning the Laws of Naval War, referring to the issue with Article 50.

[6] However the core of the rules at the start of WWI was the loose assemblage of precedents and manuals across many nations that is international customary law.

[9] The submarine, SM U-17, allowed the Glitra's crew to board lifeboats first and then towed them to shore after sinking the ship.

Fearing that American deaths would lead to the US entering the war, after each of these incidents Germany introduced new restrictions, culminating in the Sussex pledge not to sink merchant ships until they had witnessed that life boats had been launched, equating to a vow to follow a version of the cruiser rules on all theatres.

Submarine commerce raiders still retained the advantage of being able to evade the British naval blockade, and U-boat aces like Lothar von Arnauld de la Perière accumulated some of the greatest success rates in history operating in this way.

[14] In the postwar period, the official German naval history strongly criticised the WWI Admiralty for failing to adequately pursue submarine warfare under cruiser rules.

[15] At the start of World War II, many German submarines were built with deck guns and the initial order was for attacks to be in accordance with Prize rules.