プロテスタント同盟
On 12 September 1619, the Protestant Union met at Rothenburg ob der Tauber and called on Frederick not to intervene in Bohemian affairs. Other possible allies – the Dutch Republic, Charles Emmanuel I, Duke of Savoy, and the Republic of Venice – sent letters saying they would not be able to offer Frederick assistance if he accepted the Bohemian offer. Only Gabriel Bethlen offered words of encouragement.