In 1876, Zalău became the seat of the Szilágy County. After the proclamation of the Union of Transylvania with Romania (1918), by the Treaty of Trianon Zalău has been part of Romania – except between 1940 until the end of World War II, when Northern Transylvania became part of Hungary as a result of the Second Vienna Award. On 8 September 1940, upon arrival in Zalău, the Hungarian Army killed 11 people just outside the city; and the Treznea massacre occurred in the nearby village of Ciumărna on the next day.