On February 4, 1915, the German Admiralty issued a statement declaring the entire English Channel and all of the waters surrounding Great Britain and Ireland to be a war zone. This meant that all ships, even those from neutral nations, such as the United States, were subject to attack. The Germans blamed Great Britain for sailing warships under neutral flags, and declared that they could attack any ship, with or without passengers, under any flag. President Woodrow Wilson issued a strongly worded reply on February 10, warning the German government that any attack on American ships or citizens would not be tolerated, despite the official neutrality of the United States. Though Germany backed down from its stance on sinking neutral ships, the German declaration was another step toward the unrestricted submarine warfare that Germany would wage later in the war.

On February 4, 1915, the German Admiralty issued a statement declaring the entire English Channel and all of the waters surrounding Great Britain and Ireland to be a war zone. This meant that all ships, even those from neutral nations, such as the United States, were subject to attack. The Germans blamed Great Britain for sailing warships under neutral flags, and declared that they could attack any ship, with or without passengers, under any flag. President Woodrow Wilson issued a strongly worded reply on February 10, warning the German government that any attack on American ships or citizens would not be tolerated, despite the official neutrality of the United States. Though Germany backed down from its stance on sinking neutral ships, the German declaration was another step toward the unrestricted submarine warfare that Germany would wage later in the war.

Germany pursued an aggressive naval policy from the beginning of World War I. This was, in part, a reaction to the strong blockade that Britain had imposed on German ports from the beginning of the war. This blockade was key to Britain’s war aim of cutting off trade with Germany. It also prohibited the shipping of food to Germany, and by the end of the war, this would result in hundreds of thousands of German deaths from malnutrition or related causes. In retaliation for the blockade, on February 4, 1915, the German Empire announced that waters around Great Britain and Ireland were a war zone, and all ships, even those from neutral countries, could be sunk without warning.

The Imperial German Navy was outmatched by the British Royal Navy at the beginning of the war. In November 1914, Britain mined the North Sea and warned that all shipping was subject to search for supplies bound for Germany. Germany had a strong stable of U-boats (submarines), however. The German Admiralty wanted to use these to attack merchant vessels, even those of neutral countries, hoping that this would, in turn, stifle trade with Britain. The German declaration the following year was a warning that British, Russian, and French vessels would be sunk, and, since Britain was suspected of sailing its ships under neutral flags, neutral vessels would also be targeted, as of February 18. U-boats were particularly threatening because it was difficult for them to adhere to traditional rules of naval engagement, allowing for the release of passengers and the capture of the crew before a merchant ship was sunk.

President Wilson responded immediately to this threat to Americans at sea, warning Germany that the United States would take whatever steps were necessary to protect its citizens and their property. He asserted that the US government would regard any attacks on its vessels as a violation of US neutrality, and would hold the German government to “strict accountability” for such actions. In an effort to forestall US entry into the war, the German government relented a bit and pledged adherence to the traditional rules of engagement, but the German Navy continued to believe that U-boat attacks were the most effective way to gain the advantage at sea. In May 1915, a German U-boat sank the Lusitania, a British passenger ship. Nearly 1,200 people were killed, 128 of them Americans. Because of the outcry from the United States, Germany suspended U-boat warfare that September. However, it was resumed at the beginning of 1917, which helped to lead the United States into the war.

Woodrow Wilson was the twenty-eighth president of the United States. He served two terms in office, from 1913 to 1921. Wilson was dedicated to a strict policy of neutrality during the early years of World War I, and he won his reelection in 1916 with the slogan, “He kept us out of war.” Wilson spent much of his first term in office navigating the perilous course of US neutrality, which was challenged on all sides. Wilson did finally lead the United States into war on the side of the Allies (Britain, France, and Russia, among others) in 1917 as a result of Germany’s use of unrestricted submarine warfare and its secret negotiations with Mexico.

Wilson carefully crafted a letter that was a response to threatened violence against American citizens and their property. Wilson was committed, even then, to a position of neutrality, and so, his response to this aggressive German posturing needed to support this stance. At the same time, too soft a response could have persuaded Germany that the United States would not interfere with its war plans, and attacks against civilians and neutral commercial ships might commence in earnest.

Wilson began his letter with a strong statement and a veiled threat. It was the “privilege” and “duty” of the United States to point out to German leadership the “critical situation” that would arise should the proposed attacks on neutral ships commence. If merchant ships under the US flag were attacked, and American citizens killed, it would cause a crisis in the relationship between the United States and Germany. This was a slightly veiled way of asserting that such action could prompt the United States to join the war against Germany, a development that the German government wanted to avoid or at least postpone as long as possible.

Wilson also reminded the German government that according to international law, the only action Germany could take against neutral ships was to stop and search them. The sinking of a ship under a neutral flag, particularly without first examining its cargo or crew, was “an act so unprecedented in naval warfare” that Wilson could hardly believe Germany would consider it. If, as the German government had stated, belligerent ships were sailing under the flags of neutral nations, that would need to be determined by a legal search. Wilson also states that he will bring up the issue of British ships using neutral flags with the British government, but the actions of another nation could not be sufficient reason to threaten American lives. The United States had been, and would continue to be, neutral, and “open to none of the criticisms for un-neutral action to which the German Government believes the governments of certain other neutral nations have laid themselves open.” If German ships were no longer willing to respect US neutrality, it would be difficult to “reconcile with the friendly relations” between the two nations. This was another thinly veiled threat, but also a reminder of the Unites States’ intention to remain neutral if Germany did not carry out its planned attacks.

Wilson left little doubt that there would be retaliation, that he would hold Germany to “a strict accountability,” and that the United States would “take any steps… necessary” to protect its citizens. Germany must offer assurance that American vessels and lives would not be lost, as it was in both countries’ best interest that “no misunderstandings may arise.” As strongly worded a warning as this was, it did not contain specific consequences for Germany, and it failed, ultimately, to stop the sinking of the Lusitania only three months later, an attack that killed 128 American citizens. This, more than anything else, galvanized US public opinion against Germany.

The primary theme of this letter is a warning to Germany that the neutral status of the United States needed to be respected, or there would be consequences. Wilson was criticized at the time for not being more specific in his warning, but he was certain of the rightness of a neutral position and was focused on keeping the United States out of the war. He wanted to remind Germany that making an enemy of the United States was not in its best interest, but he wanted to do so without escalating the situation further. German leaders, on the other hand, struggled internally with how to best use the U-boats, which were proving to be their best naval weapon. Because of submarines’ vulnerability at the surface, however, they were often unable to identify a ship before attacking it, creating an incentive for the kind of expanded warfare outlined in the February 4 statement. The German government also felt justified in doing this because of the extent of the British blockade of Germany, which it said threatened to starve the civilian population; most specifically, Germany also accused Britain of sailing ships under neutral flags. Wilson made it very clear, however, that this gave Germany no right to treat all neutral vessels as hostile, and he demanded that American citizens and property be protected.

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• Tucker, Robert W.Woodrow Wilson and the Great War: Reconsidering America’s Neutrality, 1914–1917. Charlottesville: U of Virginia P. 2007. Print.