Ruijin-class armed merchantman
Ruijin class armed merchantman is a class of Chinese armed merchantmen of the People's Liberation Army Navy (PLAN) in its infancy, and participated in several battles against ships of the Republic of China Navy (ROCN) in the early 1950s. These ships are also frequently referred to as gunboats by Chinese. At its infancy, when first established in 1950, PLAN severely lacked large warships needed to defend the coastal regions which had been taken from the Republic of China at the end of Chinese Civil War. To meet the urgent need, a decision was made to  strengthen the newly established PLAN with armed merchantmen by converting some of the cargo ships in good condition. A total of six cargo ships from China Merchants Steam Navigation Company were selected for the conversion, all of which were American coastal freighter from the World War II era. These ships were sold to China Merchants Steam Navigation Company after the war. They are Design 427 (officially Vessel, Supply, Aircraft Repair, Diesel, Steel, 180') light cargo ships (AKL). All ships were assigned to the Eastern China Military Region Navy (ECMRN, 华东军区海军), the predecessor of East Sea Fleet. The main armament of  Ruijin class consisted of either two or three 3"/50 caliber guns and an M101 howitzer. It's worthy of note that most of the US 3-inch guns are not those left behind by ROCN when they retreated from mainland China, but instead, they were transferred to China from the former Soviet Union, who received them from the US during World War II. Because PLAN had already been using US 3-inch guns captured during the Chinese Civil War, the same guns in Soviet hands were provided to simplify logistics. The secondary armament of Ruijin class consisted of Japanese and  German guns Chinese communist force during the Chinese Civil War, including a pair of twin 3.7 cm Flak 18/36/37/43 guns, and two pairs of twin Type 96 25 mm AT/AA Guns. The lead ship of this class was lost to aerial attack by four ROCAF P-47s on May 18, 1954, and the rest of this class retired in the 1960s as domestically Chinese built frigates entered PLAN service.