The War of the League of Erfurt (German: Krieg der Erfurter Liga) is an ongoing conflict between the League of Erfurt and Austria (along with her allies). It has its base in a territorial conflict between Evangelical Bavaria and three small, neighboring Catholic states (Burgau, Oettingen, and Burggrafschaft) that emerged in 1531. Soon thereafter, Austria intervened triggering the use of the League of Erfurt to defend Bavaria.
The War of the League of Erfurt began in 1531 when Bavaria initiated its plans to annex its southern neighbours Burgau, Oettingen and Burggrafschaft, which were Catholic countries. At first, being weaker than their larger Evangelical foe, their militaries were rapidly collapsing; Austria, however, soon intervened in 1532 when her Archduke, Ferdinand I, declared that he would defend the three smaller countries, and invaded Bavaria, causing the government there to collapse. The Duke of Bavaria at the time, *TBD*, fled to Württemberg where a government-in-exile was established.
As part of the League of Erfurt, Bavaria called for her allies to come to her aid. This was followed by separate declarations of war on Austria, first by Saxony in 1533, then followed by Württemberg and Lorraine in 1534.
Austria eventually asked for help from Poland-Lithuania, in the hopes of opening a second front. Poland-Lithuania obliged, and declared war on the League in late 1534.