U.S. Naval Base Subic Bay
On 12 May 1966, "Chicago" got underway for her first Vietnam deployment. After stopping at Pearl Harbor and Yokosuka, where a new radar antenna was installed, the ship arrived at U.S. Naval Base Subic Bay on 12 June. Picking up her helicopter detachment the cruiser departed the next day for duty with Task Force 77 on Yankee Station in the Tonkin Gulf.