You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
Crimean_War

Context:
Russia, as a member of the Holy Alliance, had operated as the "police of Europe", maintaining the balance of power that had been established in the Treaty of Vienna in 1815. Russia had assisted Austria's efforts in suppressing the Hungarian Revolution of 1848, and expected gratitude; it wanted a free hand in settling its problems with the Ottoman Empire — the "sick man of Europe". The United Kingdom could not tolerate Russian dominance of Ottoman affairs, as that would challenge the British domination of the eastern Mediterranean.

Question:
Who operated as the "police of Europe"?

Russia