He travelled to Bohemia to represent Archduke Albert at the Diet of Budweis in January 1614. Shortly after his election, Emperor Matthias invited Bucquoy to take charge the Imperial Army and he accepted the post in August 1614. He happened to be on leave in the Habsburg Netherlands when on 23 May 1618 the Second Defenestration of Prague triggered the Bohemian Revolt. Bucquoy returned to Vienna in August and took command of the imperial forces raised to put down the revolt. Short of soldiers, supplies and money, his first campaign came close to disaster more than once. Defeated by Count Jindřich Matyáš Thurn on 9 November in the Battle of Lomnice, he was unable to save the besieged town of Pilsen. While his army encamped in its winter quarters around Budweis, Thurn's surprise march on Vienna was only halted by the severity of winter. After receiving reinforcements provided by Archduke Albert, Bucquoy's campaign of 1619 did much to reverse the fortunes of the war. On 10 June he defeated Ernst von Mansfeld in the Battle of Sablat, thereby forcing the Bohemians to abandon their siege of Budweis.