 This title was only used on one other occasion during his reign.A document of 1058 dates itself "in the time of the most serene prince Lord Ferdinand and his consort Queen Sancha" ("in tempore serenissimi principis domni Fredinandi et ejus conjugis Sanciae reginae") and later qualifies him as "this emperor, the aforesaid Ferdinand" ("perrexerunt ad ipsum imperatorem jam dictum Fredenandum").The "Chronicon complutense", probably written shortly after Ferdinand's death, extols him as the "exceedingly strong emperor" ("imperator fortissimus") when mentioning the Siege of Coimbra.