Q: Why was the U.S. move to unrestricted air and submarine warfare against Japan so significant? Did a precedent exist?
Joel Holwitt: With the passage of so many years since the Second World War, it may be difficult to understand why unrestricted submarine warfare could have been considered so controversial and despicable before the United States entered the war. And yet, the United States did go to war in 1917 over unrestricted submarine warfare, and during two subsequent decades, national and military leaders repeated numerous high-minded statements that nothing could be more foreign to the American notion of freedom-of-the-seas than unrestricted warfare. But within one day, the United States abruptly turned about from that position and waged a determined and pitiless maritime war against Japan that ended only in the absolute destruction of Japan’s merchant marine. For that reason alone, the U.S. decision to conduct unrestricted submarine warfare remains an important moment in history.
Q: What is "freedom of the seas?"
Nittsu Maru, on her way to the bottom in March 1943. (Photo courtesy Naval Historical Center)
JH: Freedom of the seas is a concept that has gone through numerous iterations over the centuries, but at its core it is about the right of noncombatants to travel the seas in safety during time of war. Ultimately, President Woodrow Wilson defined it as the right of any noncombatant to travel in any place at any time without threat of attack by any aggressor. Such an "absolute" definition of freedom of the seas, of course, conflicted immediately with the German U-boat campaign in the First World War.
Q: Why should we be interested in this shift in military
JH: U.S. unrestricted submarine warfare played a pivotal role in the Allied victory in the Pacific.
Despite a faltering start at the beginning, the U.S. submarine force essentially annihilated the Japanese merchant marine. The true cost of U.S. unrestricted submarine warfare, however, did not lie at sea. Rather, its greatest impact lay ashore, where untold numbers of Japanese
soldiers and civilians suffered and died from malnutrition and starvation. The U.S. submarine campaign so successfully interdicted food supplies to the home islands that during the
period immediately after the Japanese surrender, the Japanese people relied upon American food shipments to survive. And more than that, U.S. unrestricted submarine warfare implicitly legitimized the German unrestricted submarine campaign, and ended the Wilsonian paradigm of "absolute" freedom of the seas.
USS Covington sinks after being torpedoed by a German U-boat, her American colors still flying. Indiscriminate attacks by German U-boats against shipping, regardless of nationality, defenses, and passengers, proved to be the pivotal factor that drew the United States into the First World War. (Photo courtesy Naval Historical Center)
Q: What is the enduring legacy of this move on U.S. Naval policy
today? And, why was it illegal to begin with?
JH: Unrestricted submarine warfare was specifically outlawed by the London Naval Treaty of 1930 and the London Submarine Protocol of 1936, which was signed by every major power that conducted unrestricted submarine warfare in the Second World War. These clauses were meant to last "in perpetuity" regardless of what happened to the rest of the treaties. After the Second World War, the Nuremberg tribunal insisted that the 1936 London Submarine Protocol was still in effect. In fact, without any new treaties to override it, the Protocol is technically still in effect today. Therefore, by law, submarines must carry out cruiser rules of warfare by visiting, searching, and capturing merchant ships. There are some logical exceptions to this, but international law still does not permit unrestricted submarine warfare as seen in the Second World War.
The senior naval leadership of the United States, including some members of the General Board of the Navy, assembled for a group photo in December 1920. (Photo courtesy Naval Historical Center)