sentences:  In August, Mercy was killed at Second Nördlingen, where both sides suffered casualties of over 4,000 each.Although fighting continued, a military solution was no longer possible, and increased the urgency of negotiations that led to the 1648 Peace of Westphalia.The Thirty Years War began in 1618 when the Protestant dominated Bohemian Estates offered the Crown of Bohemia to fellow Protestant Frederick of the Palatinate, rather than conservative Catholic Emperor Ferdinand II.