A seaworthy satire of overblown nationalism and British social order, H.M.S. Pinafore put the wind in Gilbert and Sullivan’s sails and ushered in the modern musical theater. Composer Arthur Sullivan and librettist W.S. Gilbert armed their first internationally successful comic operetta with rousing choruses, merry character tunes, and some of the most memorable songs in the English language, including “When I Was a Lad,” a searing sendup of governmental ineptitude. Skewering the tropes of Victorian melodrama, this pageant of mismatched marriages and mistaken identity resolves in the most preposterous manner, yet remains a timeless reminder that true love triumphs over class distinction.