In 1901, at 19, she married Duke Peter Alexandrovich of Oldenburg, who was privately believed by family and friends to be homosexual. Their marriage of 15 years remained unconsummated, and Peter at first refused Olga's request for a divorce. The couple led separate lives and their marriage was eventually annulled by the Emperor in October 1916. The following month Olga married cavalry officer Nikolai Kulikovsky, with whom she had fallen in love several years before. During the First World War, the Grand Duchess served as an army nurse and was awarded a medal for personal gallantry. At the downfall of the Romanovs in the Russian Revolution of 1917, she fled with her husband and children to Crimea, where they lived under the threat of assassination. Her brother Nicholas and his family were shot by revolutionaries.