Protestant Union

For the Dutch political party, see Hervormd Gereformeerde Staatspartij. For other uses, see Protestant League.
Member states of the Protestant Union (blue) in the Holy Roman Empire, c. 1610
Many Protestant rulers were not members of the Union, most notably the Elector of Saxony. Religious fragmentation in Central Europe on the eve of the Thirty Years' War in 1618.

The Protestant Union (German: Protestantische Union), also known as the Evangelical Union, Union of Auhausen, German Union or the Protestant Action Party, was a coalition of Protestant German states. It was formed on 14 May 1608 by Frederick IV, Elector Palatine in order to defend the rights, land and safety of each member. It included both Calvinist and Lutheran states, and dissolved in 1621.