D'Iberville and the community of St. Martin share more than a common origin: from their colonial beginnings they have been one, now separated only by an invisible county line. The first is named after Pierre LeMoyne, Sieur d'Iberville, commander of the French fleet who initiated settlement of Louis XIV's claim to the Mississippi Valley and adjacent coast of the Mexican Gulf in 1699. The latter is named for Raymond St. Martin de Pattier (or Jorquiboey),...