[2] Or born about 1751 according to his obituary [3] At some point in time O'Brien had been made captain of a Philadelphia merchant ship, the Dauphin.
It was on this such ship that on July 30, 1785, about 150 miles west of Lisbon, Portugal, the Dauphin was boarded by an Algerian vessel armed with eighteen cannons.
[1] Upon their arrival in Algiers O'Brien and his men were issued rough sets of native Algerian clothing and two blankets each that were to last for the entire period of captivity which for some had ranged anywhere from between a few weeks to fifty years.
Traveling between several cities within Europe, including London, O'Brien had hoped to obtain gold and silver from London bankers and eventually succeeded in securing loans from Portugal and Italy, but, before arriving with the promised merchandise in Algiers, the ship by which O'Brien was travelling, the brig Sophia, was captured by Tripolitan pirates.
[1] Because the Maria had an Algerian passport, Bashaw Yusuf Qaramanli, the ruler of Tripoli, promptly ordered its release.