sentences:  It drew in Protestant German states like Saxony and Brandenburg-Prussia, as well as external powers like Denmark-Norway.In 1630, Gustavus Adolphus of Sweden invaded Pomerania, partly to support his Protestant co-religionists, but also to control the Baltic trade, which provided much of Sweden's income.Economic factors meant Swedish intervention continued after Gustavus was killed in 1632, but conflicted with states within the Empire, like Saxony, and regional rivals, such as Denmark.