In May 1918, the Central Powers claim a victory over another of their Eastern Front enemies when they sign the Treaty of Bucharest with Romania. The Czech Legion, trying to reach Vladivostok on the Trans-Siberian Railway, comes into open conflict with the Bolsheviks. In a conference at Spa, Kaiser Wilhelm and Emperor Charles of Austria-Hungary agree to a long-term alliance, economic agreements, and a common high command. On the Western Front, the German Army mounts its third major offensive in as many months, attacking the Allied lines on the Chemin des Dames and advancing to the Marne, where the American Army’s Third Division helps halt the German advance at Chateau-Thierry. Americans conduct their first offensive operation of the war at Cantigny. In Great Britain, the House of Commons defeats a motion by former Prime Minister Asquith to conduct a parliamentary inquiry into charges made against the government in a letter from a British general. RMS Moldavia, a British transport carrying American soldiers, is torpedoed and sunk by a German U-boat in the English Channel. The Royal Navy tries again to block U-Boat access to the sea at Ostend, this time with more success. The United States Congress enacts the Sedition Act, forbidding the use of disloyal or abusive language about the government in time of war, and the Overman Act, giving the President broad authority to reorganize federal agencies by executive action. Declaring that “politics is adjourned,” President Wilson urges Congress to stay in session through the campaign season. Air mail service begins between New York City and Washington, D.C.