did she participate in any war?
No, but she was in Russia at the outbreak of World War I.
Olga Constantinovna of Russia
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. 
who is olga constantinovna? She was Queen consort of the Hellenes as the wife of King George I. where was she born? At Pavlovsk Palace near Saint Petersburg when? UNANSWERABLE do you know who her parents are? Grand Duke Constantine Nikolaievich and his wife, Grand Duchess Alexandra did she do any social work? She supported the Amalieion orphanage and the Arsakeion school for girls located on University Boulevard.
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Olga Constantinovna of Russia [SEP] World War I
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.