On 25 May 1941, Hughes and several other women were briefed on the search for the German battleship "Bismarck". Shortly thereafter, she decoded a message referring to the "Bismarck" that detailed its current position and destination in France. The "Bismarck" was subsequently attacked by the Royal Navy and sunk on 27 May. This was the first significant victory by the codebreakers, demonstrating the utility of the project.