To break the deadlock of trench warfare on the Western Front, both sides tried new military technology, including poison gas, aircraft, and tanks. The adoption of better tactics and the cumulative weakening of the armies in the west led to the return of mobility in 1918. The German Spring Offensive of 1918 was made possible by the Treaty of Brest-Litovsk that ended the war of the Central Powers against Russia and Romania on the Eastern Front. Using short, intense "hurricane" bombardments and infiltration tactics, the German armies moved nearly to the west, the deepest advance by either side since 1914, but the result was indecisive.