At the age of fifteen he entered the drawing room of the board of ordnance at the Tower of London - a building that he would later improve.

On 7 June 1783 the governor, Sir George Augustus Eliott, afterwards Lord Heathfield, thanked him publicly for his services during the siege.

They left London with the mission but by Christmas Eve they shipwrecked among the ice at the mouth of the River Elbe.

The following June, Major Robert Hope of the royal artillery and Holloway reported upon the fortifications of the Dardanelles and successfully advised on their improvement including at Tenedos and the gulf of Saros.

A virulent attack of plague towards the end of the year caused great mortality, and carried off Koehler and his wife that December.

It was Holloway's orders to bring the Turks back to Egypt to assist a newly arrived army under the command of General Sir Ralph Abercromby.

[1] Early in the following month, the plague having ceased, the Turkish army advanced and, after crossing the desert, came in contact with a superior French force under General Belliard in May.

Holloway was in de facto command of the Turkish Army, both in the advance from Jaffa and during their countering of the French attack at the seven-hour Battle of al-Khanka on 16 May.

The mission returned home under the command of Major (afterwards Sir) Richard Fletcher, royal engineers.

For his services with the Turkish army, Holloway, who had been invested by the sultan with five different pelisses and a gold medal in November 1801.