Don Fernando Rivera y Moncada had already marked the point for a mission in what is now San Francisco, and a land expedition to establish Spanish rule over the area, under Juan Bautista de Anza had been sent northwards.

He arrived in Vera Cruz in August, 1774 and proceeded to Mexico City to receive orders from the Viceroy, Frey Don Antonio María de Bucareli y Ursua.

Ayala was designated to pass through the strait and explore what lay within, while the Santiago and Sonora continued northwards.

He tried a number of anchorages, finding that off Angel Island was most satisfactory, but failed to make contact, as he had hoped, with Anza's party.

Ayala's subsequent report to the Viceroy gave a full account of the geography of the bay, and stressed its advantages as a harbour (chiefly the absence of "those troublesome fogs which we had daily in Monterey, because the fogs here hardly reach the entrance of the port, and once inside the harbor, the weather is very clear.")