primary mission was maintaining aids to navigation. Much of her activity was driven by the annual advance and retreat of heavy winter ice on the Great Lakes. Buoys were brought to port in the fall to prevent them from being damaged, sunk, or set adrift by ice. Buoys were cleaned, repaired, and repainted over the winter and redeployed by the ship in the spring. Her second mission was icebreaking, a service she performed throughout her career. One aspect of her icebreaking work was to free ships that became trapped in the ice. In April 1960, for example, the tankers Edward G. Seubert and Clark Milwaukee became frozen-in on their way to Green Bay. Mesquite cut a track into the port, widened it, and then broke the ice near the immobilized ships to allow them to move into the broken track. The entire round trip from Green Bay, including breaking out the two tankers took nine hours. A second icebreaking role was to escort ships through the ice, breaking a channel for the ship following her. Mesquite was engaged on this task on April 18, 1958 when she led three Canada Steamship Lines ships through the ice in Whitefish Bay. A third icebreaking activity was to clear shipping lanes for future ship traffic. Mesquite cleared ice in the Straits of Mackinac, Lake Michigan, and the Saint Claire River. She also participated in "Operation Oil Can" over several winters. This program engaged several cutters in icebreaking channels for tankers transporting fuel to Great Lakes ports. Mesquite participated in numerous search and rescue missions. For example, in November 1956 the 7,300-ton freighter J.P. Wells lost her rudder in a storm with 30-foot seas. Mesquite steamed out into Lake Superior to render assistance. She was able to get lines across to the disabled ship twice, but both parted. She radioed for help and together with USCGC Mackinaw was able to tow J.P. Wells to Sault Ste. Marie for repairs. In 1963 Mesquite and a tug towed the grounded freighter Exiria off the rocks. She was laden with 500 tons of cheese embarked at Green Bay. In August of that year the ship rescued a family of five whose sailboat had been wrecked on an uninhabited island. In September 1974, Mesquite rescued five people aboard a small powerboat that had been adrift for two days with engine problems and a dead battery. She not only