In August 1914, Olga was in Russia at the outbreak of World War I, in which the Allied or Entente Powers including Russia, Britain and France fought against the Central Powers including Germany, Austria-Hungary and the Ottoman Empire. She decided to stay in Saint Petersburg and establish a military hospital to support the Russian war effort. Olga created a clinic at Pavlovsk Palace where she cared for wounded soldiers with her sister-in-law, Grand Duchess Elizabeth Mavrikievna. Other members of the imperial family, such as Princess Helen and Olga's granddaughter Grand Duchess Maria Pavlovna founded field hospitals at the front. As the war continued, Olga became aware of the growing crisis in Russia, and attempted to warn Tsarina Alexandra in 1916 of the danger of revolution but the Russian empress refused to listen. A few weeks later, Olga attracted the fury of the Tsarina after signing a petition asking for a pardon for her grandson, Grand Duke Dmitri Pavlovich, who had been exiled to the Persian front for his involvement in the assassination of Alexandra's favorite mystic, Grigori Rasputin.