Completed two years after her British homologue HMS "Duke of Wellington", "Bretagne" became the most powerful warship in the world, but commissioned too late to effectively take part in the Crimean War, which was almost over after the fall of Kinburn in October 1855. Appointed flagship of the Toulon squadron in January 1856, she sailed to the Black Sea to serve during the last months of the conflict, which came to an end in July, and helped return the French expeditionary corps back to France. She was then part of the training squadron in Toulon, cruising between Sardinia and Spain.