He joined the army in 1782, serving with the 36th Regiment of Foot in India in 1784 and as aide de camp to General Thomas Bruce in Ireland in 1787.

When the French Revolutionary War began in 1793, he took a force of volunteers to reinforce the Flanders Campaign, where he fought at the Battle of Tournay.

Later in the year Walker was promoted to colonel and, after a period of leave and independent service, re-joined the 50th in time to fight in the Walcheren Campaign of 1809.

Walker was promoted to major-general in 1811 and given command of a brigade in the 5th Division with which he fought at the Siege of Badajoz in 1812, during which he was badly wounded in a diversionary attack.

His paternal great-great-grandfather was Sir Walter Walker, advocate to Catherine of Braganza, the wife of King Charles II.

[Note 1][2][3][4][5][6] Walker was promoted to lieutenant in the 95th on 13 March 1783, serving on Jersey, but the regiment was disbanded on 31 May as part of the cut-downs at the end of the American Revolutionary War.

He then volunteered to go with new recruits to the army of the Duke of York on the Flanders campaign in March, as part of which he fought at the Battle of Tournay on 10 May 1794.

[7][9][4] After having been used to fulfil several confidential missions which took him to The Hague, Rotterdam, and Amsterdam, in early 1795 Walker was appointed Inspector of Foreign Corps, for the purpose of which he was sent to south-west Germany and Switzerland.

When the allied campaign against France began to falter in April 1795 Walker took command of the regiment and took it to Civitavecchia in Italy where they embarked for England in August 1796.

[3] He served as an Inspecting Field Officer of Recruiting in Manchester between February 1798 and March 1799, during which time on 6 September he was promoted to lieutenant colonel in the 50th Regiment of Foot.

He briefly commanded this regiment in Portugal in early 1799, but was posted to the British military mission assisting the Russians in the Anglo-Russian invasion of Holland in October.

The brigade was not broken up after the Copenhagen campaign, and instead sailed in December to attack naval installations at Cadiz and in the Mediterranean Sea.

The brigade's naval transports were upset by constant bad weather as they travelled south, however, and they only reached Gibraltar in March 1808, by which time the opportunity to attack the installations had gone.

[13] Walker and his regiment were not left idle for long after this, forming part of the army of Lieutenant-General Sir Arthur Wellesley that landed in Portugal on 6 August.

Wellesley, now Lord Wellington, removed the British troops from the expedition and instead used it as a diversion from his manoeuvres around the city of Ciudad Rodrigo.

Walker cajoled his men into continuing the attack despite this, and it would go on to be successful, but soon after he was shot in the chest from very close range by a musket, the bullet of which was deflected by his pocket watch but still entered his body, and then bayoneted four times in the proceeding fighting.

He lost a great amount of blood and had several ribs broken; it was thought he might die at one point and he was so weak that he was unable to be moved from Badajoz for four months after the fighting had ended.

[19][21][22] After having been sent home to continue recuperating from his wounds in August, Walker was made colonel of the Regiment de Meuron, a Swiss mercenary unit, on 24 October.

[19][3][23] Prior to Walker's arrival, the army had fought the Battle of the Pyrenees and the 2nd Division's commander, Lieutenant-General William Stewart, had been wounded during this.

In October the commander of the 7th Division, Lieutenant-General Lord Dalhousie, left the peninsula and on 18 November Walker was appointed as his temporary replacement.

[19] Shortly after this Walker learned that his wife had died on 15 February, and considering the poor state of his existing wounds he decided to leave the peninsular army.

Between April 1815 and February 1817 he served as Governor of Grenada and for this he was made a Knight Grand Cross of the Order of the Bath upon his return.

It has been suggested that his climbing of the ranks was assisted by an unknown benefactor, perhaps a member of the Royal Family; his father was given an apartment at Hampton Court Palace upon his retirement and Walker's initial appointment to the 95th was brought about by Queen Charlotte.

[27] One officer who served in the 50th said of him that he was: "endued with extraordinary coolness and intrepidity of mind, knew right well how to go about his work...with a remarkably handsome set of features, animated by keen expressive eyes, that were full of intelligence and fire.