The western coast of North America had been partially explored in 1542 by Juan Rodriguez Cabrillo who sailed for the Spanish, but as England was in conflict with Spain, Drake decided to claim the rest of North America that Spain did not control.
However, Drake was uneasy with inaccuracies in the published accounts of his voyages, and in 1592, he wrote to Queen Elizabeth in reference to "the certain truth concealed, as I have thought it necessary myself" and requested that the accounts be rewritten accordingly [REF].