During the 1930’s, the Swedish Landsverk company, like many other European arms manufacturers, wished to capitalize on the growing tensions on the continent in order to secure new production and licencing contracts. Among the most profitable markets was the one for new armored fighting vehicles. As a result, Landsverk began developing a whole range of new combat vehicles during the 1930’s, aimed solely at the export market.

Among them was the L-60 light tank, whose basis Landswerk used to develop the larger and heavier Lago tank. While the L-60 saw some commercial success, the Lago tank received little interest from foreign customers. However, after some time passed, the Swedish military changed their doctrine and sought to procure a medium tank themselves. Given that Landsverk already developed the Lago, Swedish military officials turned to the company with the orders to further develop the design.

In the end, the Lago tank went through multiple prototype stages and was ultimately used only as a testbed for the development of the subsequent Strv m/42 and Pvkv m/43 tanks. The vehicle never had any production orders and didn’t take active part in any conflicts. Due to its design however, the Lago I can be seen as the first true domestically built Swedish medium tank.