Lacy (Lasi, Lasci, Lascay), Peter Edmund (Pyotr Petrovich) (1678–1751), the ‘Prince Eugene of Muscovy’, Russian field-marshal, was born 29 September 1678 in Killeedy, Co. Limerick, son of Pierce Edmund de Lacy of Ballingarry, Co. Limerick, and his wife Maria (née Courtney). At the age of thirteen he joined the prince of Wales's regiment as an ensign, commanded by his uncle James Lacy. Having served at the first siege of Limerick he left Ireland with Patrick Sarsfield (qv) after the treaty of Limerick (1691), together with his uncle Col. John Lacy, landed in Brest, and joined the regiment of Athlone as lieutenant. He also saw service in Piedmont under Marshal Catinat and fought at Marsaglia in 1693. Unable to gain employment in the Hungarian service after the disbanding of the regiment of Athlone following the treaty of Ryswick in 1697, he entered the Polish service under the duc de Croy, who recommended him to Peter the Great as a member of a hundred-strong detachment of officers employed to train the Russian army.
He served against the Swedes in Livonia and Ingria and later commanded the Grand Musketeers, a group of a hundred Russian nobles armed and mounted at their own expense. In 1705 he became major of Scheremetoff's regiment in Poland and served against the Swedes. In the following year he became lieutenant-colonel of the regiment of Polotsk and for his valour at the siege of Bucko was promoted colonel of the regiment of Siberia and repeatedly distinguished himself against Charles XII, the warrior king of Sweden. At the head of two regiments he again defeated the Swedes at Peregova (November 1708) and blocked their attempts to bridge the Desna. He stormed Rumna the following month and held it against the whole Swedish army. The tsar gave him command of a regiment of grenadiers and credited the Russian victory at Poltava (July 1709) to his suggestion that the Russian troops hold their fire for close quarters. Between 1709 and 1721 Lacy served against both the Danes and Swedes and commanded a daring amphibious assault against Sweden in 1720–21 which brought him within twelve miles of Stockholm.
In 1723 he was summoned to take his seat in the College of War, and rode behind the imperial carriage at the coronation of the new tsarina Catherine in 1725. In the same year he became a knight of the order of Alexander Nevsky and commander-in-chief of St Petersburg, Ingra, and Novgorod. In 1726/7 the tsarina dispatched Lacy to expel Maurice de Saxe, later marshal of France, from the duchy of Courland. In 1733 he accompanied his confederate General Munnich into Warsaw to establish Augustus of Saxony on the Polish throne in opposition to Stanislas Leszczynski. When Danzig was reduced after 135 days, Augustus rewarded him with the order of the White Eagle. In 1733 he drove Stanislas from Thorn. Later at Busawitza, at the head of less than 2,000 men, he routed an army of 20,000, an action that finally decided the war of the Polish succession. He later joined an imperial army under Prince Eugene, the ‘Atlas of the Holy Roman Empire’, to campaign against Stanislas's French allies. The carriage and conduct of Lacy's troops greatly impressed the veteran commander. However, peace was concluded and he received the patent of field marshal on his way back from a visit to the imperial court in Vienna.
On the outbreak of war with Turkey the following year Lacy was sent to reduce Azov. The Turkish bashaw finally capitulated after three months, leaving behind 300 pieces of ordnance and nearly 300 Christian captives. The following year Lacy received supreme command of the Russian forces in the Crimea. He attacked Azov, a town and fortress of great strength (March) and took it in twelve days. He then stormed the previously impregnable fortress at Perekop, which surrounded the castle of the aga of the Guards on the Don and the Dneiper. He later captured the Crimean stronghold of Kaffa at the head of a force of 30,000 Cossacks, overran the Crimea as far as the Tauric mountains, and ravaged the countryside with fire and sword. In 1739–41 his forces were held in reserve in the Ukraine as a consequence of renewed hostilities with Sweden, and he later commanded against the Swedes in Finland.
Lacy took no part in the coup that brought Tsar Peter's niece Elizabeth to the throne in 1741, but his intervention in a mutiny among the Russian Guards was said to have ‘saved St Petersburg and perhaps the empire’ (O'Callaghan, Irish brigades, 494). Returning to the Finnish theatre, he succeeded in capturing the fortified town of Frederickshamn without the loss of a single man. He chose to ignore orders to conclude the campaign, engaged a force of 17,000 Swedes at Helsingfors (Helsinki), and forced them to capitulate. The new tsarina joined him on his ship for the celebrations and presented him with a ring of great value and a golden cross. Lacy pressed on with a vigorous assault on Hongo. His final push against the Swedish capital Stockholm was frustrated only by the conclusion of the war.
Lacy retired to his estates at Livonia, where he died 11 May 1751 at the age of 72. He left an estate of £60,000. According to contemporary accounts, he was tall and well made, cool in judgement, ready in resource, rapid and decided in action. Frederick the Great of Prussia called him the ‘Prince Eugene of Muscovy’ (DNB).
He married Countess Martha Phillippina Feuchen, formerly Countess Frolick, a widow whose family held estates at Loeser, southern Livonia. They had five daughters, one of whom married Gen. George Browne (qv), one of his successors as governor of Livonia. His eldest son served in the Polish–Saxon service and later became a count of the Holy Roman Empire. His second son Francis Maurice (Franz Moritz) served his military apprenticeship under his kinsman, the famous Count Ulysses Von Browne. He later served with great distinction under the Austrian general Count Leopold Daun at Reichenberg and Prague.
Letters written by Lacy (1733–42) survive in the university library of Uppsala. De Linge, a friend of Lacy's son Franz Moritz, published a ‘Journal of Peter Lacy’, which was probably dictated by the ailing marshal from scattered notes. A typescript of an unpublished life of Marshal Lacy by John Jordan, along with numerous biographical and bibliographical notes, is in the NLI. A portrait of Lacy is reproduced in Wills, The Jacobites and Russia, 1715–50 (2002), between pp 144–5.