Context: The Waldensian refusal to obey the Edict of 25 January 1655 led the government to send troops to plunder and burn Waldensian houses, and to station over 15,000 soldiers in their valleys. On 24 April 1655, the Piedmontese Easter commenced: a massacre of 4,000 to 6,000 Waldensian civilians was committed by ducal troops. This caused a mass exodus of Waldensian refugees to the Valley of Perosa , and led to the formation of rebel groups under the leadership of Joshua Janavel, Jean Leger and Bartolomeo Jahier, whilst several states including England, France, Germany and the Protestant cantons of Switzerland attempted to intervene diplomatically. On 18 August, the Pirenolo Declaration of Mercy was issued, which constituted a peace treaty between Charles Emmanuel II and the Waldensians.

Question: How many months after the Piedmontese Easter commenced was the Pirenolo Declaration of Mercy was issued?

Answer:
4