It is believed that between 1680-1683 he served under Percy Kirke in Tangier. Kirke later relieved the City of Londonderry. John Mitchelburne had a majors commission from the Prince of Orange dated 5th of February 1689, and in the same month he played his part in the attempt on Carrickfergus.
He was one of the Protestant officers cashiered by Tyrconnell. Taking service with the `Hillsborough Consult` in the countries and Antrim and Down forces, being with them at the "Break of Drumore" as well as at Coleraine in the attempt to hold the Bann Passage in the retreat on Derry. Preliminary to the investment of the City he was most energetic not only in the field, but in the military council used his every endeavour to force Lundy into more determined action. After James was refused at the City Gates, and the flight of Lundy, he was heart and soul with the citizens in the organisation of their forces and preparation for the resolute defence.
On April, 19th he was appointed to command the remnants of " The Skeffington Regiment" which he carried out with honour and success till the end of the Siege.
mnay Sallies took place outside the walled city in which Mitchelburne and his regiment took an active role. It is stated in an old diary that whilst parading outside the walls one of Mitchelburnes regt` was killed by cannon fire from Strongs Orchard (now St columbs` park and Ebrington Barracks).
On the 1st May, 1689 during the siege some misunderstanding between Gov` Baker and Mitchelburne, whereupon both drew swords upon each other. Col, Mitchelburne was put under confinement. However, the matter was so tedious that he was never tried by a council of war. Shortly afterwards on the 17th, June Baker fell ill and during his illness Mitchelburne acted as Governor. Baker died June 27th and it is stated that he nominated Mitchelburne to act as joint Governor with Rev. George Walker. He also acted as pall bearer at Bakers funeral, which cast doubts on the seriousness of their disagreement.
By all accounts Mitchelburne and Walker acted as joint Governors so that while one was involved in sallies the other could be working in the civil administration of the city. He maintained this position until the relief on the 28th, July when an excitied throng anxiously awaited news of the arrival of the relief ships. Wherupon Walker and Mitchelburne when Kirke entered the City handed over to him the reins of the office.
On the 7th, May at four in the morning Mitchelburne and Walker were involved in the battle of the Windmill which was situated opposite Bishops Gate 350 yards from the ramparnts. This had been taken the previous night by the enemy under the command of Brig. Gen. Ramsey. Fighting lasted only half an hour, 200 of the enemy were killed and 500 wounded. 300 of those died later. Many stands of colours were captured, tho of which fell into the hands of Mitchelburne. Brig. Gen. Ramsey and many of his superiour officers were slain in this action.
Mitchelburne was married with seven children, unfortunately he lost his wife and all his children during the siege either from hunger or disease. He later remarried. His second wife is believed to have been the daughter of another defender, Capt. Michael Cunningham of Prehen Londonderry, there was no children from this marriage.
After the relief of the city; Kirke whom I earlier stated served along side Mitchelburne in Tangier commissioned as sole Governor of the City and made him sole Governor of the City, and also made him Colonel of both Skeffingtons and Croftons Regt`s which he ably fused into one. He commanded this corps at the Boyne, and managed to muster 664 rank and file after the bloody battle was over. He served at the long Siege of Sligo which surrendered on condition that the garrison should march to Limerick with their arms and baggage, and he took possesion of it on the 16th September 1691 and was made Governor.
