Escorted by three escort vessels and a United States Navy blimp, the convoy proceeded up the coast of New Jersey to New York City, where on 6 October 1942 "John W. Brown" began loading her first cargo – 8,380.9 long tons (9,386.6 short tons; 8,515.0 metric tons) of cargo destined for the Soviet Union, consisting of two Curtiss P-40 Warhawk fighters, 10 M4 Sherman tanks, 200 motorcycles, 100 jeeps, over 700 long tons (784 short tons, 711 metric tons) of ammunition, and over 250 long tons (280 short tons, 254 metric tons) of canned pork lunch meat – at Pier 17 in Brooklyn. While in New York, she also had the Oerlikon 20 mm cannon mounted on her bow replaced by a 3-inch (76.2-mm) 50-caliber gun, and she interrupted her loading of cargo on 9 October 1942 for work on the degaussing and compass adjusting ranges. With loading complete on 14 October 1942, "John W. Brown" departed New York on 15 October on her maiden voyage, bound for the Persian Gulf, where she would unload her cargo for delivery overland to the Soviet Union. Her 14,400-nautical mile (16,560-statute mile; 26,667-km) route was designed to allow her to avoid the areas where Axis forces posed the greatest threats to shipping. She made the first leg of the voyage in convoy, steaming down the United States East Coast to Guantanamo Bay, Cuba, where she joined another convoy for the trip across the Caribbean Sea to the Panama Canal. After passing through the canal and reaching the Pacific Ocean, she steamed alone down the west coast of South America, requiring two weeks to reach Cape Horn. She then made a 17-day independent crossing of the South Atlantic Ocean to Cape Town, South Africa, where she stopped for two days to refuel and reprovision. Getting back underway, she steamed alone north through the western Indian Ocean off the east coast of Africa, and anchored in the Persian Gulf on 25 December 1942, two and a half months after leaving New York. Ports in the Persian Gulf were overwhelmed by the amount of cargo arriving from allied countries, and so "John W. Brown" was forced to lie at anchor for a month until she could begin to unload at Abadan, Iran, where she dropped off the two P-40s and some of the tanks in late January 1943.