1937年上海寄美国水路实寄封1件，贴伦敦一版孙像5分1枚，京版烈士10分2枚，销上海8月18日戳，保存完好，此封寄出时正值淞沪会战开始，上海吴淞口于8月14日被日军舰队封锁，所有船隻无法出海，直到8月18日吴淞口解除封锁，此封正是吴淞口解除封锁首日所寄出ChinaPostal HistoryRepublic of China1937 (18 Aug.) envelope to U.S.A. bearing Dr S.Y.S. 5c. and Martyrs 10c. (2) tied by Shanghai c.d.s. Right at the beginning of the Battle of Shanghai (also known as Stalingrad on the Yangtze), Chinese force block the coast to deny the Japanese the opportunity to land reinforcements on 14 Aug, thus this mail can only send on the 18th until the re-open of Woosungkou.
