On 23 May 1618, the Bohemian Protestant nobles defeated King Matthias and threw the Roman Catholic governors of Bohemia from a window of their office at Prague Castle in an act which came to be known as the Defenestration of Prague. The new government, formed of Protestant nobility and Heinrich Matthias von Thurn, assumed command over the Bohemian Protestant forces.
A Roman Catholic army under the command of Charles Bonaventure de Longueval, Count of Bucquoy was approaching Prague but a Protestant army stopped it near Čáslav for several weeks; subsequent problems with food supplies and illness forced Buqouy to withdraw. Later, when Buquoy was on his way to reinforce, Count Thurn followed Buquoy's army and forced a battle near the village of Lomnice nad Lužnicí in southern Bohemia. Part of the Roman Catholic army held a position between two ponds and suffered most of its casualties from artillery fire. Buquoy suffered defeat, losing at least 1,500 troops. As a result, the main part of the Roman Catholic army had to leave Bohemia. But the Protestants did not follow up their victory by chasing the enemy, thereby missing an opportunity to crush the Roman Catholic army.