Algernon Sidney

English politician and political theorist Algernon Sidney (c. 1623–1683) argued eloquently against tyranny and the divine right claimed by hereditary monarchies. An active participant in the English Civil War, he first put pen to paper after witnessing the violence and turmoil of that period, but during the equally retributive Restoration, he was convicted of treason and publicly beheaded.

Descended from a marital union of families with close ties to the Tudor monarchs, Algernon Sidney served in the incendiary English Long Parliament of 1640–60. He was conflicted about the most fateful moment of the English Civil War, the execution of King Charles I in 1649, and went on to produce his most enduring work as a political philosopher, Discourses Concerning Government, in which he set forth the principles of good governance and a legal framework that protects it. “A flock cannot subsist under a shepherd that seeks its ruin, nor a people under an unfaithful magistrate,” Sidney would declare in this work.

Sidney's place of immense privilege and status in Jacobean England begins with the central London address that marked his place of birth on or around January 14, 1623. Baynard's (or Barnard's) Castle was a landmark property located near the River Thames and the old wall constructed by Roman legions circa 200 CE. The castle changed owners several times but had been built by King Henry VIII for the first of his wives, Catherine of Aragon. The former royal palace became part of the Sidney family holdings via the earls of Pembroke, whose wealth and standing at King Henry's court derived from their ties to Catherine Parr, the woman who became the Tudor monarch's sixth wife.

Algernon Sidney

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Educated in France

Sidney was the second son of Robert Sidney, Second Earl of Leicester, and Dorothy Percy, daughter of the ninth earl of Northumberland. The couple's marriage produced seven children who lived to adulthood, and their families had firm connections to the Tudor court. Robert Sidney's paternal grandfather, the first earl of Leicester, was one of the closest advisors to Henry VIII's daughter, Queen Elizabeth I, and the Sidney family's primary residence, Penshurst Place in Kent, was a gift from Henry VIII. The Percys had an equally illustrious record of loyalty and service to the crown; the Northumberland peers controlled significant parcels of land in northeastern England that served England as a buffer against Scottish incursions and ensured access to North Sea shipping routes.

The childhood years of Sidney and his older brother Philip marked a period of enormous change in England and continental Europe. Queen Elizabeth's successor, James I, died in 1625 and the next English monarch, Charles I, was deeply enmeshed in the political and religious fallout of Henry VIII's break with the Roman Catholic Church in the 1530s. Of particular concern at the time was Charles's decision to marry French princess Henrietta Maria. Queen Henrietta maintained her allegiance to the Roman Catholic faith despite the fact that her new husband was by decree the head of the Anglican Church, which gave him primacy status equal to that of the pope in Rome.

The English royal couple also had conflicting links to powerful empire-states in Europe whose fortunes derived from commerce and industry—as in the case of fellow Protestant princes in Germany and the Low Countries—or from the global efforts to expand imperial power conducted by Spain and France during the early 17th century. These competing dynastic, religious, economic, and political claims served up a potent stew of trouble, and Charles blundered into expensive foreign wars, including a fiveyear clash early in his reign that was part of the 30 Years' War. Closer to home, religious tensions and the powers of ecclesiastical authority throughout the British Isles went unchecked or were exacerbated by King Charles I and his decrees. This fomented unrest in various counties and shires, a few of which began to assert their authority by strengthening local militias.

The careers of both Algernon Sidney and his elder brother Philip were shaped by their early education in France in the 1630s. The boys were close to their father, a member of parliament (MP), military officer, and diplomat of some renown, and they likely accompanied him on missions abroad during their teen years as well as to Ireland when Charles I elevated Robert Sidney to the title of Lord Lieutenant of Ireland. Charles had violated longstanding power-sharing arrangements between the crown and the titled peers that stretched back to the historic Magna Carta of 1215. Like other titled landholders and elected members of the House of Commons, the second earl of Leicester objected to the imposition of onerous taxes on lands and estates, a burden Charles levied to finance his ongoing foreign wars. Conversely, Charles I was provoked by the threat of recalcitrant English, Scottish, and Irish barons to add to existing militias in response to authoritarian decrees from the throne.

Wounded at Marston Moor

The English Civil War erupted in 1642 and pitted Parliamentarians—also known as Roundheads—against the Royalists (also called Cavaliers) loyal to the king. Algernon and Philip joined the Parliamentarian side and took up arms as members of the Army of the Eastern Association, a Roundhead force comprised of militias raised among the great landed estates of southern England. As a lieutenant colonel serving in North Yorkshire, the 21-year-old Algernon Sidney was seriously injured during the Battle of Marston Moor in July of 1644.

Sidney had voted against Charles's execution and clashed with Cromwell, who in 1653 dissolved Parliament and assumed power as Lord Protector of the Commonwealth of England, Scotland, and Ireland. For much of the 1650s, Sidney shuttled between London and the rural homes of relatives, among them his Percy cousins in Petworth in southern England. He was among the concerned Parliamentarians alarmed when Cromwell died suddenly in 1658, and there was a brief and disastrous attempt to install Cromwell's inexperienced son as Lord Protector. The Cromwellian Protectorate was dissolved the following year, whereupon Sidney traveled abroad as part of a diplomatic delegation to forge a peace agreement over Baltic and North Sea maritime rights.

“Every Man … a Soldier”

Sidney was still away when the slain king's son was restored to the throne as King Charles II. Fearing for his safety, he spent the next seven years in Italy, France, Switzerland, and Germany. He survived two known assassination attempts, one in Rome and the second in the southern German city of Augsburg in the spring of 1665. While in Augsburg he wrote Court Maxims, in which he argued against the divine right of kings, a legal principle with origins in the Roman Church of the early medieval period. “Monarchy is the worst evil that can befall a nation,” he contended in this work, the existence of which was discovered in the 1970s by historian Blair Worden. The three sections of Court Maxims contain imagined dialogues between two pseudonymous Greek philosophers, Philalethes and Eunomius. “He that without law brings a people under his Power,” Eunomius asserts in one quote beloved by staunch libertarians, “I look on as a Tyrant, Thief, publick Enemy, against whom every man is a Souldier.”

Despite fears for his life, Sidney returned to England in 1667 and took up residence at the home his father had built in London, Leicester House. His brother Philip had by now been granted a pardon for his involvement in the English Civil War, and he inherited their father's title and estates after the death of the 2nd Earl of Leicester in 1677. The brothers subsequently fell out, and Sidney would initiate a civil action against Philip over the inheritance.

Sidney is sometimes cited as a participant in the Rye House Plot of 1683, a planned assassination of King Charles II and his brother James, Duke of York, although such reports are scarce and of questionable veracity. The scheme took its name from the moat-surrounded manor house in Hoddesdon, Hertfordshire, that was purportedly the place from which the royal siblings would be seized while en route to a thoroughbred horse race at the Newmarket grounds in Suffolk. Although the plot failed when the race was canceled, Sidney was caught in the wide net of suspected plotters. He was arrested on June 26, 1683, and the manuscript he was writing at the time, Discourses Concerning Government, was seized by bailiffs. It was admitted as evidence during his trial in early November of 1683.

Beheaded at Tower Hill

During the English Restoration period, a minimum of two witnesses was necessary under English law to affirm that the defendant had uttered his intent to commit treason. Sidney was convicted on the testimony of only one man, William Howard, 3rd Baron Howard of Escrick, who was widely known as a dissembler. The Lord Chief Justice permitted the Discourses Concerning Government manuscript to be admitted as a second “witness” to Sidney's alleged crime. In his defense, Sidney gamely argued that, because Discourses had not been published, it could not be considered evidence. Ultimately, the crown prosecutor maintained that scribere est agere—to write is to act—and Sidney was among the 14 Rye House plotters sentenced to death. Seven of the men were hanged, drawn, and quartered, a particularly heinous form of capital punishment that was especially popular among the London public. Sidney's station afforded him a more dignified and swift execution: beheading at the block on Tower Hill on December 7, 1683.

Discourses Concerning Government was published, posthumously, in 1698 and it would shape Republicanist political movements against absolute monarchies in the eventful century that followed. Sidney wrote it in response to Patriarcha: A Defence of the Natural Power of Kings Against the Unnatural Liberty of the People, a 1680 tract by monarchist Robert Filmer, who suffered heavy property losses during the English Civil War. Drawing from his personal experiences during the same war and in competing parliaments, Sidney posited that a carefully constructed independent judiciary could serve as an effective check when an executive authority—a sovereign or prime minister, for example—was deadlocked in opposition to a legislative body.

Sidney also shared his opinion of human nature and a government's innate tendency toward rot. “Men are so subject to vices and passions, that they stand in need of some restraint in every condition; but most especially when they are in power,” he declared in Discourses Concerning Government. “The rage of a private man may be pernicious to one or a few of his neighbours; but the fury of an unlimited prince would drive whole nations into ruin: And those very men who have lived modestly when they had little power have often proved the most savage of all monsters, when they thought nothing able to resist their rage.”


Brennan, Michael G., The Sidneys of Penshurst and the Monarchy, 1500–1700, Routledge, 2017.

Houston, Alan Craig, Algernon Sidney and the Republican Heritage in England and America, Princeton University Press, 2014.

Scott, Jonathan, Algernon Sidney and the English Republic 1623–1677, Cambridge University Press, 1991.

Scott, Jonathan, Algernon Sidney and the Restoration Crisis, 1677–1683, Cambridge University Press, 1988.

Sidney, Algernon, Court Maxims, edited and with an introduction by Hans W. Blom, Eco Haitsma Mulier, and Ronald Janse, Cambridge University Press, 1996.

Sidney, Algernon, Discourses Concerning Government, A. Millar, 1751. □

(MLA 8th Edition)