Charles Emmanuel I, Duke of Savoy
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.