The territory around Bauska was originally inhabited by Semigallian tribes. In the mid-15th century, Bauska castle was built by Germans of the Livonian Order. The city started developing in its present day location around 1580, receiving its city rights in 1609.
After the Livonian War Bauska became part of the Duchy of Courland. The castle and city suffered heavily in the 17th and 18th centuries, under attack from Sweden in the Polish-Swedish War and the Russians in the Great Northern War. In 1711 an outbreak of plague ravaged Bauska, exterminating half of the population, and war returned once more in 1812, when Bauska became one of Napoleon's army's transit point en route to Moscow.
After the wars, Bauska enjoyed a period of stability, and grew as a trade center between Riga and Lithuania. Many inhabitants were merchants or worked in ceramic-making, but there was a large brewery as well. Bauska was primarily built of wooden houses: in 1823, only 6 of the 120 houses within the city were built of brick or stone. For this reason, devastating fires were not uncommon. Historically, all social affairs had been in the hands of the German gentry. In the 18th century, however, many Jews moved to the city, and by 1850 made up half the population, diluting the strong German influence.
The city was taken by the German Imperial Army in 1915, and roughly half the population fled. In 1916, the Germans installed the city's first electrical grid. After a short occupation by the Red Army, the Germans retook and held the city, until 1919, when the Latvian army drove the Bermontians out of Bauska for good.
From 1918 to 1940, the proportion of ethnic Latvians in the population grew strongly, making up 75% of the population, though the Jews and Germans still maintained a noticeable presence. In 1939, just before World War II, virtually the entire German population of Bauska repatriated to Germany, causing the city to lose one of its traditional ethnic
