Graubünden - not a member of the Confederation but an associate - suffered badly during the 30 Years War, partly because of its geographical position, and partly because of its administrative structure and religious composition.

All the warring parties coveted its strategically vital Alpine passes, which were the only available route between Austria and Spanish-ruled northern Italy - both of them Habsburg territories. Control of the passes determined whether or not the Empire could move troops from one field of war to another.

Graubünden at the time was not a centralised entity but a federation of three regions, the Leagues, whose loose political structure made it vulnerable to outside powers.

In addition, it was split along religious lines. In particular the subject territory of the Valtellina (Veltlin) on its southern borders, was largely Catholic and resented the dominance of the Protestants. In the "Holy Bloodbath" of 1620, the Valtellina Catholics, backed by Spanish troops from Milan, massacred large numbers of their Protestant neighbours.

This event sparked intervention from the great powers, and the area changed hands several times. The best known local leader was Jörg Jenatsch (1596-1639), a Protestant pastor. He allied himself to the French, whose forces under the Duc de Rohan drove the Austrians from the Valtellina. But finding that France intended to keep control of the area, Jenatsch converted to Catholicism and allied himself with the Habsburgs. He was assassinated in 1639, but his aim of preserving the Valtellina for Graubünden was achieved.