Valmy was laid down at Brest in 1838 as Formidable and launched in 1847. When she entered service in 1849, she was the largest warship in the world and would remain so until 1853,[citation needed] when the British three-decker Duke Of Wellington (6,071 tons and converted to steam power while on the stocks) entered service, but she would remain the largest sailing three-decker ever built. Unlike most similar ships, that featured a pronounced tumblehome, she had vertical sides; this significantly increased the space available for upper batteries, but reduced the stability of the ship; wooden stabilisers were added under the waterline to address the issue.