SIDNEY (Algernon), was second son of Robert earl of Leicester. During the civil wars, he adhered to the interest of parliament, in whose army he was a colonel; and was nominated one of the king's judges, though he did not sit among them. He was a zealous republican; and consequently a violent enemy to Cromwell, after he had made himself protector. In 1659 he was appointed by the council of state to go with Sir Robert Honeywood, and Bullstrode White-locke, Esq; commissioners to the Sound, to mediate a peace between the kings of Sweden and Denmark. At the restoration, colonel Sidney would not personally accept of the oblivion and indemnity then generally granted to the whole nation, but continued abroad till 1677, when he obtained from the king a particular pardon, upon repeated promises of constant quiet and obedience for the future. In 1683, however, he was accused of being concerned in the Rye-house plot; and after the lord Russell had been examined, he was next brought before the king and council. He said that he would make the best defence he could, if they had any proof against him; but he would not fortify their evidence by any thing he should say; so that the examination was very short. He was arraigned for high treason before the lord chief justice Jeffreys at the king's bench, tried, found guilty, and beheaded in
1683. He wrote Discourses on Government, which have been often printed, and are esteemed decisive authorities in politics; inasmuch, that some have declared them an ample recompence for the loss of Cicero's six books De Republica. It is certain they abound with strong sense and good learning; and show their author to have been very consummate in the knowledge of human nature and civil polity.