Colonel Robert Boyd was appointed from the First foot guards to the colonelcy of the Thirty-ninth regiment on the 6th of August 1766, in succession to Lieut.-General Adlercron, deceased.
1767.
During the years 1766, 1767, and 1768, the regiment continued to be stationed in Ireland.
1769.
In the year 1769 the Thirty-ninth again proceeded to Gibraltar; and while serving in that garrison, events transpired which enabled the regiment to acquire additional honor.
1779.
The possession of this fortress by the English had been regarded by the Spaniards with great jealousy, but every effort for its recovery had signally failed. The contest between the colonists in North America and Great Britain, seemed to offer the Spanish monarch a favourable opportunity for regaining possession of Gibraltar. The French monarch, in the previous year, had concluded a treaty of defensive alliance with the American colonies, which involved Great Britain in a war with France. The Court of Versailles subsequently engaged that of Madrid to take a part in the contest, and on the 16th of June 1779 the Spanish ambassador presented a manifesto at St. James’s, equivalent to a declaration of war, and immediately departed from London; and shortly afterwards the siege of Gibraltar was commenced by the Spaniards, the anticipated reduction of that important fortress being one of the principal objects which induced Spain to become a party in the contest.
Gibraltar was accordingly beset, by sea and land, by the Spanish fleets and armies. The following return shows the strength of the garrison at the commencement of the blockade on the 21st of June 1779:—
| British. | Officers. | Men. | |||
| Royal Artillery | 25 | 460 | |||
| Royal Engineers | 8 | 114[15] | |||
| 12th foot | 29 | 570 | |||
| 39th ” | 29 | 557 | |||
| 56th ” | 27 | 560 | |||
| 58th ” | 28 | 577 | |||
| 72nd ” (Royal Manchester Volunteers), disbanded in 1783 | 33 | 1013 | |||
| —— | —— | 4030 | |||
| Hanoverian. | |||||
| Hardenberg’s regiment | 29 | 423 | |||
| Reden’s ” | 27 | 417 | |||
| De La Motte’s ” | 33 | 423 | |||
| —— | —— | 1352 | |||
| Total | —— | 5382 |
The Thirty-ninth regiment was commanded by Brevet Lieut.-Colonel William Kellett, major of the corps, and the garrison, mustering five thousand three hundred and eighty-two men, was under the orders of General the Right Hon. George Augustus Eliott, afterwards Lord Heathfield. Being thus blockaded by sea and besieged by land, the troops at Gibraltar became cut off from communication with other countries, and the garrison appeared a little world within itself.[16] The arrangements for the defence were devised with judgment, and executed with skill. The soldiers cheerfully conformed to the strict rules which their circumstances rendered necessary, and severe exercise and short diet became habitual to them; at the same time the great importance of the place, and the determined character of General Eliott and his garrison, occasioned this siege to be regarded with universal interest by the several nations of Europe.