Mr. Henderson was one of those ministers who went with the Scots army to England in the year 1640, every regiment having one of the most able ministers in the bounds where they were raised as chaplain, and when the treaty was set on foot which began at Rippon, and ended at London, he was also one nominated as commissioner for the church, the duties of which he discharged with great prudence and advantage, and the very next year, he was, by the commission of the general assembly, authorized to go with lord Loudon, Warriston and Barclay, to the king, to importune him to call his English parliament, as the only and best expedient to obtain an honourable and lasting peace; but his embassy had not the desired effect.
After his return, he was chosen moderator to the general assembly anno 1643, and when the English commissioners, viz. Sir William Armyn, Sir Harry Vane the younger, Mr. Hatcher and Mr. Darly from the parliament, and two ministers, Mr. Stephen Marshal a presbyterian, and Philip Nye an independent, from the general assembly of divines at Edinburgh, where the general assembly of the church of Scotland was then fitting, craving their aid and counsel upon such an emergent occasion, he was among the first of those nominated as commissioners to go up to the parliament and assembly of England. And so in a little after, Mr. Henderson and Mr. Gillespie, with Mr. Hatcher and Mr. Nye, set out for London to get the solemn league ratified there (the rest of the commissioners staying behind until it should be returned). Upon their arrival at London, and having received a warrant from the parliament to sit in the next assembly (which warrant was presented by Mr. Henderson), the assembly sent out three of their number to introduce them; at their entry Dr. Twisse the prolocutor welcomed them unto the assembly, and complimented them for the hazard they had undergone on their account both by sea and land, in such a rigorous season (it being then November); after which they were led to a place the most convenient in the house, which they kept ever after[64].
Again in the year 1646, being sent down from London to attend the king, then with the Scots army at Newcastle, at which time the general Assembly appointed also Messrs. Robert Blair, James Guthrie, Robert Douglas, and Andrew Cant, to wait on his majesty; here Mr. Henderson officiated for some time as his chaplain; and although he and Mr. Blair, of all the presbyterians were the best beloved of the king, yet they could by no means prevail upon him to grant the first demand of his subjects, yea, he obstinately refused, though they besought him on their knees.
In the interval of these affairs, a series of letters was continued betwixt the king, assisted by Sir Robert Murray on the one hand, and Mr. Henderson on the other; the one in defence of Episcopacy, and the other of Presbytery, which were exchanged from the 10th of May to the midst of July as each person was in readiness.
But during this controversy, Mr. Henderson's constitution much worn out with much fatigue and travel, he was obliged to break off an answer to the king's last paper, and to return to Edinburgh, where, in a little time after his arrival, he laid down his earthly tabernacle in exchange for an heavenly crown, about the middle of August 1646.
Some of the abettors of prelacy, sensible of his great abilities, were earnestly desirous to bring him over to their side at his death[65], and for that purpose palmed upon the world most groundless stories of his changing his principles at his last hours; yea, the anonymous author of the civil wars of Great Britain goes farther, when he says, page 200. "Mr. Henderson had the honour to be converted by his majesty's discourse at Newcastle, and died reconciled to the church of England." But from these false calumnies he hath been sufficiently vindicated a long time ago, by a declaration of the 9th act of the general assembly in 1648. See also Mr. Logan's letter in vindication of Mr. Henderson, from these aspersions cast on him by Messrs. Sage and Ruddiman.
Some time after his death a monument was erected on his grave in the Gray-friar's church-yard of Edinburgh, in form of a quadrangular urn, inscribed on three sides; and because there was some mention thereon of the solemn league and covenant (or rather because Mr. Henderson had done much for and in behalf of the covenant), commissioner Middleton, some time in the month of June or July 1662, stooped so low as to procure an order of parliament, to raze and demolish said monument, which was all the length their malice could go against a man who had been near sixteen years in his grave. Hard enough, if he had died in the prelatical persuasion, from those who pretended to be the prime promoters of the same[66].
Mr. Henderson was a man who spared no pains in carrying on the work of reformation in that period.——For whether he was called forth to church-judicatories, to the pulpit, or any other business, no trouble or danger could make him decline the work. One of his colleagues and intimate acquaintances give him no mean testimony, when he says, "May I be permitted to conclude with my earnest wish, that that glorious soul of worthy memory, who is now crowned with the reward of all his labours for God and us, may be fragrant among us as long as free and pure assemblies remain in this land, which, I hope, shall be to the coming of our Lord. You know he spent his strength, wore out his days, and that he did breathe out his life in the service of God, and of this church; this binds it on us and posterity, to account him the fairest ornament after Mr. John Knox of incomparable memory, that ever the church of Scotland did enjoy[67]."
Beside the forenamed papers, with another intitled the remonstrance of the nobility, &c. a tract on church government, and an instruction for defensive arms, &c. the general assembly appointed him, Mr. Calderwood and Mr. Dickson, to prepare a directory for the worship of God, which not only had the desired effect, but at length brought about uniformity in all our churches. There are also some few of his sermons in print, some of which were preached before the parliament.