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Captain Alexander Cavalié Mercer

Waterloo 200

of Exeter

Captain Mercer's "G" Troop

28 Mar 1783 - 9 Nov 1868

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Submitted by: Robert Pocock

Date added: 19 May 2015

Surely the most famous and quoted of all junior officers at Waterloo, the name Mercer has become synonymous with ‘saving the Brunswickers’ and the repulse of French cavalry on the afternoon of 18th June 1815.

Today a stone monument on the allied ridge marks the last position of Mercer’s famous “G Troop” of six Royal Horse Artillery guns. Across Belgium and the Netherlands the name Mercer is also cited and celebrated by local historians thanks to a French translation of his outstanding work, Journal of the Waterloo Campaign.

Amidst all the first-hand accounts of the battle, Mercer’s Journal of the Waterloo Campaign stands out as the most extensive and finest account of the campaign, perhaps of any military campaign, ever. So who was this man? Descended from the Mercers of Aldie and Meikleour, his ancestors being buried in St John's Kirk Perth since the 12th century. There is added spice from the Cavalié origins, yet our Mercer was very much an Englishman. Born in 1783 in Cottingham near Hull, Mercer’s father was a General in the Royal Engineers. At 6 months old Mercer and his family moved to London whilst his father took a posting to Jamaica, an unhealthy destination due to the risk of disease.

Enjoying a charmed upbringing amongst the Ambassador set, his father returned to London when Mercer was 6, just as the French Revolution was kicking off, taking the family with him on his latest posting to Guernsey. An unsettled schooling and the death of his mother in childbirth left Mercer to follow his elder brother’s footsteps into the artillery just as he turned 15. Having learned his trade at the Royal Military Academy in Woolwich, he was posted first to Plymouth and then to Ireland, dealing with domestic riots and uprisings.

Attachment to the Royal Horse Artillery in 1804, amongst the élite of the armed forces, was followed in 1806 by a transfer to G Troop RHA, which was to remain his home until beyond Waterloo. Under the tutelage of Augustus Frazer, the finest horse artilleryman of his time, Mercer and G Troop were honed into an efficient fighting machine.

His first overseas campaign in 1807 was an ignominious one. Two invasions of South America, focused on Montevideo and Buenos Aires, led to surrender, and Mercer covered the retreat. Back in England whilst his colleagues were achieving glory and fame under Wellington in the Peninsula, in 1809 G Troop was posted to Woodbridge, Suffolk to defend the coast.

Years of barrack duty and practice went unrewarded, although Frazer did secure a transfer to the Peninsula and so Mercer, whilst still a 2nd Captain, took command. Mercer married in late 1813, yet the exile of Napoleon to Elba in 1814 brought hope of advancement to a close. The barracks of Woodbridge were broken up, and the Troop moved to Colchester to await reductions. The news of Napoleon’s return brought one last opportunity to achieve recognition, and G Troop had the pick of horses and equipment as they set off on campaign.

Mercer’s Journal of the Waterloo Campaign tells of the journey to Ostend, through Bruges, Ghent and on to the lush farmland of the Dender valley awaiting the start of hostilities. A keen and often amusing observer of people, landscape and architecture, Mercer’s Journal is also a great companion for sightseeing in the area. At the British cavalry parade on 29th May Blücher, commander of the Prussian forces commented that each of G Troop’s outstanding horses was fit for a Field Marshal.

Awoken early on the morning of 16th June, G Troop marched with the cavalry in sweltering heat, unsure of their orders, only to arrive too late to participate at the battle of Quatre Bras.

Yet the 17th was to bring heroics, as Mercer recounts in his Journal, commanding his G Troop in the retreat through torrential downpours. It seems the day was made for Mercer when he spotted Napoleon, who had long been the scourge of Europe.

On the morning of 18th, G Troop formed part of the reserve artillery. Mercer’s initial desire to support Major Lloyd’s foot artillery led to a reprimand, following which he was posted to the right rear of the allied line. Receiving some light incoming fire, Mercer disobeyed Wellington’s orders and commenced counter-battery fire, only to receive the attention of much heavier fire. He desisted, but only after G Troop had sustained its first casualty.

Mid afternoon Frazer galloped up with the urgent order to move to the centre of the line, and to expect attack by cavalry on arrival. Mercer’s Journal describes; “We breathed a new atmosphere - the air was suffocatingly hot, resembling that issuing from an oven. We were enveloped in thick smoke, and malgré the incessant roar of cannon and musketry, could distinctly hear around us a mysterious humming noise, like that which one hears of a summer’s evening proceeding from myriads of black beetles; cannon-shot, too, ploughed the ground in all directions, and so thick was the hail of balls and bullets that it seemed dangerous to extend the arm lest it should be torn off.”

Mercer just had time to slap his guns into position when the French cavalry crested the rise 100 yards away. Double-shotted with case-shot (canisters containing hundreds of musket balls) and roundshot his cannon piled up French men and horses before them, as each fresh discharge increased the carnage before them. Charge after charge, the effect was the same.

Over his shoulder the Brunswick infantry in square were composed of young soldiers, and Mercer decided to remain at his guns, again against orders, rather than retire to the safety of the infantry squares. When the French cavalry retired they took individual shots at Mercer, and yet despite close shaves from both bullet and cannon-ball he remained untouched.

Towards the end of the day the French artillery fire became hotter than ever, as G Troop were enfiladed from the side until saved by fresh allied artillery. Exhausted by their exertions, they collapsed and slept where they had fought. Firing over 700 rounds on the day, at last Mercer and G Troop had their moment of glory.

On the morning of the 19th Mercer’s Journal reflects seriousness, sensitivity and compassion as his men sought to give succor to the wounded.

Mercer’s Journal then tells of the march to Paris, and his frustration at finally achieving promotion to full Captain, but at the cost of leaving his beloved G Troop. Briefly returning to England in the Autumn he found his wife seriously ill, his first son dead and a newborn infant also dead. His father died in 1816, and sadly his wife died following childbirth in 1817, although that son, named Cavalié, went on to lead an accomplished life.

Left alone in the world with a young son to raise, Mercer also found himself a victim of post-war reductions. He served firstly in the Corps of Royal Artillery Drivers, before being placed on half-pay. Rejoining in 1823, he sailed to Quebec, and after breaks of leave and a return to England, he was posted in 1938, now as Lt Colonel, to Halifax, Nova Scotia. His paintings from the time are now treasured by Canadians as an early record of their nation.

After a period commanding at Dover, he settled in Exeter, a City that he had often delighted in during his younger days. He never fully retired, reaching the rank of full general in 1865, just three years before his death at the age of 85.

One of eight RHA troops at Waterloo, why has Mercer and G Troop become the most famous? The other RHA troop captains had already achieved brevet promotions to the army rank of Major or Lt Colonel, some carrying a knighthood or CBE. These RHA troops led by Bean, Bull, Gardiner, Ramsay, Ross, Webber-Smith and Whinyates all performed with great gallantry, with Bean and Ramsay killed in action, and Bull, Webber-Smith and Whinyates wounded.

Many artillery officers also left first-hand accounts of the battle, most particularly in response to Siborne’s requests in compiling a cartographic and written record of the Battle. Yet none left such a distinguished literary account of the entire campaign. Whilst many were exposed to fire and danger for longer, none delivered such a sustained intensity of fire. Mercer’s fame is also partially due to his disobeying of orders, and to the fact that he was, by far, the most junior RHA troop commander at Waterloo (and the British do have a habit of admiring the under-dog).

Mercer did not live to enjoy his fame. His son published his Journal in 1870, two years after Mercer’s death. Today the proud memory of Mercer’s G Troop RHA are sustained by G Parachute Battery (Mercer’s Troop), 7 Para RHA who remain based at Colchester.

Today, Mercer’s Waterloo sword is on display at Firepower, the Royal Artillery Museum in Woolwich.

Mercer’s grave is also being restored for the Waterloo 200 commemorations, and a book of Mercer’s prized watercolours has also been published. You can learn more and get involved by visiting

Mercer’s direct DNA expired on the death of his son, yet many Mercers remain rightly proud of their kin’s achievements. In the absence of any direct descendants, this article has been written by Mercer historian Robert Pocock.


Journal of the Waterloo Campaign, General Cavalié Mercer, published by William Blackwood and Sons 1870

Royal Artillery Historical Trust

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