From the beginning of the Second World War the sea became a vitally important scene of conflict. Great Britain relied on receiving supplies by sea and, therefore, a total blockade of the United Kingdom was one the main objectives of Hitler's Germany. The British government was forced to maintain a strategy of antisubmarine warfare throughout the conflict, while the Royal Navy sought to interrupt the Third Reich's maritime traffic. In these circumstances the submarine became an important weapon of war. Headed by Karl D nitz, who would later succeed Hitler as Head of State, the German U-boats gained the initiative in the sea war and from the beginning launched all-out attacks against shipping en route to Great Britain. One of the great unanswered questions of the war is what would have happened if Hitler had granted the numerous requests made by D nitz for more submarines?