His father was now very ill, and after much difficulty Sidney obtained leave to come to England in the autumn of 1677. Lord Leicester died in November; and legal business connected with other portions of the succession detained Sidney from returning to France as he had intended. He soon became involved in polit ical intrigue, joining, in general, the country party, and holding close communication with Barillon, the French ambassador. In the beginning of 1679 he stood for Guildford, and was warmly supported by William Penn, with whom he had long been intimate, and whom he is said (as is now thought, erroneously) to have helped in drawing up the constitution of Pennsylvania. He was defeated by court influence, and his petition to the House, com plaining of an undue return, never came to a decision. His Letters to Henry Savile, written at this period, are of great interest. He was in Paris, apparently only for a short while, in Nov. 1679. Into the prosecution of the Popish Plot Sidney threw himself warmly, and was among those who looked to Monmouth, rather than to William, to take the place of James in the succession, though he afterwards disclaimed all interest in such a question. He now stood for Bramber (Sussex), again with Penn's support, and a double return was made. He is reported on Aug. i o, 1679, as being elected for Amersham (Buckingham) with Sir Roger Hill. When parliament met, however, in Oct. 168o, his election was declared void. But now, under the idea that an alliance be tween Charles and William would be more hostile to English lib erty than would the progress of the French arms, he acted with Barillon in influencing members of parliament in this sense.
Upon the dissolution of the last of Charles's parliaments the king issued a justificatory declaration. This was at once answered by a paper entitled A Just and Modest Vindication, etc., the first sketch of which is imputed to Sidney. It was then, too, that his most celebrated production, the Discourses concerning Govern ment, was concluded, in which he upholds the doctrine of the mutual compact and traverses the High Tory positions.
For a long while Sidney kept himself aloof from the duke of Monmouth, to whom he was introduced by Lord Howard. After the death of Shaftesbury, however, in Nov. 1682, he entered into the conferences held between Monmouth, Russell, Essex, Hamp den and others. That treasonable talk went on seems certain, but
it is probable that matters went no further. The watchfulness of the court was, however, aroused, and on the discovery of the Rye House Plot, Sidney, who had always been regarded in a vague way as dangerous, was arrested while at dinner on June 26, 1683.
His papers were carried off, and he was sent at once to the Tower on a charge of high treason. For a considerable while no evidence could be found on which to establish a charge. Jeffreys, however, was made lord chief-justice in September; a jury was packed; and, after consultations between the judge and the crown lawyers, Sidney was brought to listen to the indictment on Nov. 7.
The trial began on Nov. 21; Sidney was refused a copy of the indictment, in direct violation of law, and he was refused the assistance of counsel. Hearsay evidence and the testimony of the perjured informer Lord Howard, whom Sidney had been instrumental in introducing to his friends, were first produced.
This being insufficient, partial extracts from papers found in Sidney's study, and supposed only to be in his handwriting, in which the lawfulness of resistance to oppression was upheld, were next relied on. He was indicted for "conspiring and com passing the death of the king." Sidney conducted his case through out with skill. Against the determination to secure a conviction, however, his courage, eloquence, coolness and skill were of no avail, and the verdict of "guilty" was given. On Nov. 25, Sidney presented a petition to the king. The necessity, however, of check ing the hopes of Monmouth's partisans caused the king to be inexorable. The last days of Sidney's life were spent in drawing up his Apology and in discourse with Independent ministers. He was beheaded on the morning of Dec. 7, 1683. His remains were buried at Penshurst.
An edition of the Discourses concerning Government, contain ing his letters, the report of his trial, and the "Apology" written in his last hours, was published in 1763, and reprinted in 1772, with corrections and additions. There is a notice of Algernon Sidney in the preface to Collins's Sidney Papers, and some letters of his appear in that collection. See also A. C. Ewald, Life and Times of Algernon Sidney (2 vols., 1873) ; and the life by C. H.
Firth in the Dictionary of National Biography. (0. A.; X.)