Medieval merchant city (before 1795)
Thanks to its location on the confluence of two major rivers Kaunas was important for trade since its establishment in the Medieval era. By this time most of the trade went by rivers as there were no roads in Lithuania and everything was surrounded by lush forests. Unfortunately, rivers were also used by enemy forces and the main enemy of Lithuania in those days were the Teutonic Order. Kaunas castle was built in the 14th century to deter them from this strategic location.
Kaunas of the 1300s had German merchants of Hanseatic league among its inhabitants. In this era, the first churches were built. After Lithuania's Christianisation, they were soon joined by more magnificent gothic religious buildings in the early 1400s as the city expanded still centered around the City Hall square.
Despite its mercantile importance, Kaunas was not a capital of any voivodship at the time. It was part of Trakai voivodship of the Grand Duchy of Lithuania and had a peak population of 10 000.
Fortress city of the Russian Empire (1795-1918)
First time Kaunas came to political prominence was only after the demise of the Grand Duchy. In 1843 Russian Empire (which has captured Kaunas in 1795) chose it as the capital of newly formed Kaunas Governorate that included approximately half of today's Lithuania. Moreover, Kaunas was made the seat of a Catholic diocese. Political and religious importance was followed by military one as the Imperial government chosen the city as a site for a new class I fortress.
The city was transformed by massive construction. Nine forts sprung up around the city (in years 1882 - 1915), with redoubts, batteries to support them and the Central Fortification as the inner ring of defense. To the east of the Old Town, the New Town was built with all the administration and housing for officers as well as the impressive Sobor and what is now known as the Freedom Avenue. Soldiers lived in yet other new or heavily expanded districts: Freda, Panemunė, Šančiai. Many of them continue to lay there in cemeteries. By the year 1896 military personnel made up 28% of the entire Kaunas population of 68 000.
The fortress was never completed with a new fort erected every few years. After the first outer circle of defense was completed (seven forts by 1891) the government ordered the construction of a new one further from the city center. However, the advent of modern warfare changed everything and when the war against Germany finally started (the fortress was built mainly having such conflict in mind) in 1914 the mighty Kaunas fortress fell after a siege that lasted only a couple of weeks (1915). No new fortresses of this size have been constructed in the world ever since.
Temporary capital of interwar Lithuania (1918-1939)
In 1918 Lithuania became independent, but with the Polish occupation of Vilnius city (1920) Kaunas was declared "Temporary capital" and therefore the seat of government, parliament, and president. This was the golden age of Kaunas. In 20 years the city was transformed from a provincial outpost into a modern city, "swallowing" suburbs of Vilijampolė and Aleksotas while the number of people increased by 66% (92 000 to 153 000) as urbanization drive reached the agricultural Lithuania. New stately buildings sprung up in Naujamiestis and the district of Žaliakalnis was laid for the elite of the day. Almost entire high society of Lithuania resided in Kaunas - the country's top politicians and army officers, artists and sportsmen, local and foreign diplomats. It was a place of Lithuania's only international airport with flights to Koenigsberg, Riga, Smolensk and beyond; the home to Lithuania's sole opera theater, publishing houses, political intrigues and so on.
Cultural heart of occupied Baltics (1940-1990)
After the Soviet occupation of Kaunas (1940-1941 and again after 1944), the city's high society and the middle class faced heavy repressions. Tens of thousands were killed or exiled to Siberia, many to their deaths, others were murdered outright. The majority of Kaunas Jews, mostly residing in Vilijampolė district, were killed by the Nazi Germany (its occupation lasted from 1941 to 1944). By 1945 the city population went down to 80 000.
Despite heavy losses, Kaunas remained a center of Lithuanian culture it became between the World Wars. Unlike in Vilnius or Klaipėda where Russians made a third of the population by 1959, in Kaunas their share never exceeded 10%. This was very important because in the Soviet Union Lithuanians had to learn the Russian language while Russians were not taught Lithuanian at schools thus making Russian the lingua franca for interethnic communication. In Vilnius and Klaipėda, therefore, Lithuanian language became less commonly heard in streets while in Kaunas it remained prevalent. Even in sheer numbers, there were more Lithuanians in Kaunas than either Lithuanians in Vilnius, Latvians in Riga or Estonians in Tallinn, this making Kaunas a kind of the cultural heart of the occupied Baltics.
A Lithuanian writer Tomas Venclova claims in his book that in some 1950s Kaunas was regarded by Lithuanians to be more of a city than Vilnius as in Kaunas the lifestyle was urban whereas in Vilnius, not a true capital of independent state for centuries, a more rural lifestyle prevailed with its residents herding chickens or pigs.
Other Lithuanians regarded people of Kaunas to be good entrepreneurs, something that was illegal in the Soviet Union. In the 1970s it was in Kaunas where student Romas Kalanta self-immolated in protest against the Soviet rule triggering further student demonstrations. It was the Kauno Žalgiris basketball team which battled CSKA Moscow in what effectively became political battles on the basketball court.
Under the Soviet rule, the city had been expanding northwards and was connected to Vilnius and Klaipėda by four-lane highways. Continuing urbanization increased its population to 214 000 in 1959 and 376 000 in 1980.
Second city of modern Lithuania (1990-)
In 1990 Lithuania was re-established with capital in Vilnius. The importance of Kaunas somewhat declined since and its population numbers were hit hard, decreasing from 418 000 in 1989 to mere 321 000 in 2011. A large share of Kaunas elite moved to Vilnius and many emigrated abroad.
While the post-independence economic growth started in Vilnius by ~1995 and then went to the seaport of Klaipėda it reached Kaunas by around 2003 with new office buildings and two major shopping centers (Akropolis and Mega) constructed. After Lithuania joined the European Union Ryanair started flying to Kaunas and brought in more tourists. In 2011 the 17 000 seat Kaunas Arena was opened and it was the place of the final matches of the 2011 European Basketball Championship.