 There they heard word of the ongoing hostilities between the U.S. and Mexico forces and sent a message by special courier back to Commodore (Rear Admiral) John D. Sloat, commander of the Pacific Squadron then visiting Mazatlán Mexico.On May 17, 1846, this courier's messages informed Commodore Sloat that hostilities between the U.S. and Mexico had commenced.Commodore (Rear Admiral) John D. Sloat and four of his vessels were then at anchor in the harbor of Mazatlán, Mexico.