In 1415 an attack was made on Ceuta, a strategically located North African Muslim enclave along the Mediterranean Sea, and one of the terminal ports of the trans-Saharan gold and slave trades. The conquest was a military success, and marked one of the first steps in Portuguese expansion beyond the Iberian Peninsula, but it proved costly to defend against the Muslim forces that soon besieged it. The Portuguese were unable to use it as a base for further expansion into the hinterland, and the trans-Saharan caravans merely shifted their routes to bypass Ceuta and/or used alternative Muslim ports.