H.M.S. Pinafore; or, The Lass That Loved a Sailor is a
comic opera in two acts, with music by Arthur Sullivan
and a libretto by W. S. Gilbert. It opened at the Opera
Comique in London, on 25 May 1878 and ran for 571
performances, which was the second-longest run of any
musical theatre piece up to that time. H.M.S. Pinafore
was Gilbert and Sullivan's fourth operatic
collaboration and their first international