The Outlook in the West
In November 1916, Allied leaders again met at Chantilly to devise plans for the coming year. In their discussions, they determined to renew the fighting on the 1916 Somme battlefield as well as mount an offensive in Flanders designed to clear the Germans from the Belgian coast. These plans were quickly altered when General Robert Nivelle replaced General Joseph Joffre as commander-in-chief of the French Army. One of the heroes of Verdun, Nivelle was an artillery officer who believed that saturation bombardment coupled with creeping barrages could destroy the enemy's defenses creating "rupture" and allowing Allied troops to break through to the open ground in the German rear. As the shattered landscape of the Somme did not offer suitable ground for these tactics, the Allied plan for 1917 came to resemble that of 1915, with offensives planned for Arras in the north and the Aisne in the south.
While the Allies debated strategy, the Germans were planning to change their position. Arriving in the West in August 1916, General Paul von Hindenburg and his chief lieutenant, General Erich Ludendorff, began construction of a new set of entrenchments behind the Somme. Formidable in scale and depth, this new "Hindenburg Line" reduced the length of the German position in France, freeing ten divisions for service elsewhere. Completed in January 1917, German troops began shifting back to the new line in March. Watching the Germans withdraw, Allied troops followed in their wake and constructed a new set of trenches opposite the Hindenburg Line. Fortunately for Nivelle, this movement did not affect the areas targeted for offensive operations (Map).
America Enters the Fray
In the wake of the Lusitania sinking in 1915, President Woodrow Wilson had demanded that Germany cease its policy of unrestricted submarine warfare. Though the Germans had complied with this, Wilson began efforts to bring the combatants to the negotiating table in 1916. Working through his emissary Colonel Edward House, Wilson even offered the Allies American military intervention if they would accept his conditions for a peace conference before the Germans. Despite this, the United States remained decidedly isolationist at the beginning of 1917 and its citizens were not eager to join what was seen as a European war. Two events in January 1917 set in motion a series of events which brought the nation into the conflict.
The first of these was the Zimmermann Telegram which was made public in the United States on March 1. Transmitted in January, the telegram was a message from German Foreign Secretary Arthur Zimmermann to the government of Mexico seeking a military alliance in event of war with the United States. In return for attacking the United States, Mexico was promised the return of territory lost during the Mexican-American War (1846-1848), including Texas, New Mexico, and Arizona, as well as substancial financial assistance. Intercepted by British naval intelligence and the US State Department, the contents of the message caused widespread outrage among the American people.
On December 22, 1916, the Chief of Staff of the Kaiserliche Marine, Admiral Henning von Holtzendorff issued a memorandum calling for the resumption of unrestricted submarine warfare. Arguing that victory could only be achieved by attacking Britain's maritime supply lines, he was quickly supported by von Hindenburg and Ludendorff. In January 1917, they convinced Kaiser Wilhelm II that the approach was worth the risk of a break with the United States and submarine attacks resumed on February 1. American reaction was swift and more severe than anticipated in Berlin. On February 26, Wilson asked Congress for permission to arm American merchant ships. In mid-March, three American ships were sunk by German submarines. A direct challenge, Wilson went before a special session of Congress on April 2 declaring that the submarine campaign was a "war against all nations" and asked that war be declared with Germany. This request was granted on April 6 and subsequent declarations of war were issued against Austria-Hungary, the Ottoman Empire, and Bulgaria.
Mobilizing for War
Though the United States had joined the fight, it would be some time before American troops could be fielded in large numbers. Numbering only 108,000 men in April 1917, the US Army began a rapid expansion as volunteers enlisted in large numbers and a selective draft instituted. Despite this, it was decided to immediately dispatch an American Expeditionary Force composed of one division and two Marine brigades to France. Command of the new AEF was given to General John J. Pershing. Possessing the second-largest battle fleet in the world, the American naval contribution was more immediate as US battleships joined the British Grand Fleet at Scapa Flow, giving the Allies a decisive and permanent numerical advantage at sea.
The U-boat War
As the United States mobilized for war, Germany began its U-boat campaign in earnest. In lobbying for unrestricted submarine warfare, Holtzendorff had estimated that sinking 600,000 tons per month for five months would cripple Britain. Rampaging across the Atlantic, his submarines crossed the threshold in April when they sunk 860,334 tons. Desperately seeking to avert disaster, the British Admiralty tried a variety of approaches to stem the losses, including "Q" ships which were warships disguised as merchantmen. Though initially resisted by the Admiralty, a system of convoys was implemented in late April. The expansion of this system led to reduced losses as the year progressed. While not eliminated, convoys, the expansion of air operations, and mine barriers, worked to mitigate the U-boat threat for the remainder of the war.