Before sailing from the United States Porter had been instructed to pose as Sir James Yeo and was to join the _Constitution_ and _Hornet_, which two vessels were to pass as the _Acasta_ and _Morgiana_, off Cape Frio, Brazil. This was done to deceive the enemy. When Porter learned that there was a letter at Fernando de Noronha addressed to “Sir James Yeo,” he at once sent a present of porter and cheese to the governor of the island and received the coveted letter. It was found to contain the usual references of a voyage by a British commander, but some “key words” induced Porter to hold the letter to the flame of a candle, when the following instructions, written in sympathetic ink, became legible: “I am bound off Bahia, thence off Cape Frio, where I intend to cruise until the 1st of January. Go off Cape Frio, to the northward of Rio de Janeiro, and keep a lookout for me. Your friend.” Captain Porter did as ordered, but on December 29 the _Constitution_ captured, after a hard fight, the British frigate _Java_, and soon afterward the _Hornet_ sank the English sloop of war _Peacock_. This left the _Essex_ free to choose her own course and the result was her memorable cruise of two years in the Pacific. But the most remarkable instance of early marine wireless was that of the chase after the _Constitution_ from Boston, across the Atlantic, by a powerful British squadron, which, on March 10, 1815, cornered _Old Ironsides_ in Port Praya, near the extreme western coast of Africa, on the very day she entered that harbor and just seventy-six days after the hostile vessels had sailed from the blockade of the New England port. For more than eight months British cruisers had been holding the dreaded _Constitution_—then commanded by Captain Charles Stewart—in the Hub, but, late in December, 1814, she gave them the slip and once again was in blue water. Running down to Bermuda, where he captured the merchant ship _Lord Nelson_, Stewart stood across the Atlantic to the Madeiras and then cruised for several days within sight of the Rock of Lisbon. Shaping her course southward again the _Constitution_, on February 20, 1815, after a brilliant fight, captured the British cruisers _Cyane_ and _Levant_ and with his two prizes entered Port Praya on the morning of March 10. Soon after the _Constitution_ made her escape from Boston, a terrific snow storm, lasting several days, compelled the English blockading squadron to take refuge in Cape Cod Bay. On December 22, while the British officers were making themselves as comfortable as they could in the bitter cold, the English 18-gun brig sloop _Arab_, Captain Henry Jane, arrived with the startling information that the _Constitution_ had escaped. At once there was a hurrying and scurrying for immediate pursuit. Provisions, bought at an exorbitant price from the canny landfolk, were hurried aboard and every preparation was made for a chase of indefinite length.