Walter Butler, an Irish soldier of fortune, one of the assassins of Wallenstein, died near Schorndorf, Germany, in September, 1634. He early enlisted as a private in the imperial army, and became an officer of the Irish legion of which one of his relatives (in the Polish and afterward in the Spanish service) was colonel. In 1631 he was captured in defending Frank-fort-on-the-Oder against Gustavus Adolphus, at whose intercession he was speedily ransomed on account of his youth and bravery. In 1632 Wallenstein appointed him colonel of a regiment of dragoons, chiefly Irish, and rewarded him munificently for his valor in the Bohemian campaign, and especially at the capture of Eger. Misunderstandings arose between them, but Wallenstein continued to confide in the fidelity of Butler, whom he permitted to escort him with other officers to the castle of Eger. Here Butler, in connivance with Piccolomini, became an accomplice with Gordon, Leslie, and Deveroux in the assassination of Wallenstein, Feb. 25, 1634. The emperor rewarded Butler by conferring upon him the titles of count, chamberlain, and general, and by presenting him with extensive domains.

He died shortly after his participation in the battle of Nordlingen, Sept. 6, 1634, and was buried in Bohemia. He bequeathed large sums to Roman Catholic missions, and made donations to his sister and to Deveroux, who succeeded him in the command of his regiment. He figures as one of the characters in Schiller's Wallemtein. See Carve, Itinerarium, cum Historia Facti Butleyi, Gordon, Lesly et Aliorum (3 vols., Mentz and Spire, 1640-46).