Embriaco was probably born in the late 1030s, but did not gain fame until he and his brother Primo di Castello landed at Jaffa in June 1099 with a squadron of galleys: two, according to the "Annales" of Caffaro di Rustico, and six or nine according to Raymond of Aguilers. The expedition was a private undertaking. He and Primo initially marched south towards Ascalon, but an Egyptian army forced them to march inland towards the Siege of Jerusalem, then in progress. The lumber from their dismantled ships was converted into siege towers which were instrumental in the successful taking of the city on 15 July. It was there that Embriaco earned his sobriquet Caputmallei or Testadimaglio, meaning "mallet head".