The father was, like the grandfather Samuel Constant de Rebecque (1676–1782) (who reached the rank of lieutenant-general), a Swiss officer in the service of the Dutch Republic.

Jean Victor Constant de Rebecque married Isabella Catharina Anna Jacoba baroness van Lynden (1768–1836) in Braunschweig on 29 April 1798.

He started a journal that year that he faithfully kept every day of the rest of his life, thereby providing useful source material to historians.

[3] Rebecque played a very prominent role in the organization from scratch of the armed forces of the Kingdom of the United Netherlands in 1813–1815.

Nevertheless, because Rebecque had long served as a staff officer in Wellington's army, he was well acquainted with British procedures, and knew his opposite numbers personally.

Threatened by this military build-up the Great Powers declared war on Napoleon personally and started to prepare for the inevitable showdown.

Belgium has always been an important theatre of war in the course of the centuries, but in 1815 it had been peaceful since the victory of the French revolutionary armies in 1794, and most generals involved had last campaigned in the country when they were young officers, if at all.

[citation needed] Wellington himself had traversed the country on his way to Paris in 1814 and he had at that occasion scouted the area around Waterloo and was aware of its advantages as a battlefield in case Brussels was to be defended.

It was generally recognized that the first road would be the prime venue for the French to reach Brussels, and the second one was indispensable for maintaining communications between the two Coalition armies.

He was already in Charleroi before the French were discovered and when news of this sudden appearance reached Wellington he still worried that this was just a feint, and that the true advance would come by way of Mons.

Because of this possibility of being outflanked, and being cut off from the escape route to the coast, Wellington on the evening of 15 June decided to concentrate his army around Nivelles.

[citation needed] These orders to the 2nd Brigade, 2nd Netherlands Division under major-general Prince Bernhard of Saxe-Weimar-Eisenach, at Quatre Bras at the time, would have evacuated this essential strategic point.

As Saxe-Weimar was aware of the oncoming French because he heard firing from the vicinity of Frasnes, and saw the alarm beacons lighted, the order to evacuate surprised him.

He immediately reported this decision to the Prince of Orange in Brussels, who informed Wellington of it at the famous ball of the Duchess of Richmond.

Had Marshal Michel Ney succeeded in occupying the crossroads and the road to the north, as Napoleon intended, the way would have been wide open for the French to quickly march north after their victory at Ligny; Brussels would probably have fallen, without Wellington being able to do anything about it; and with the fall of Brussels king William's little project of the Kingdom of the United Netherlands would have failed and his budding country might have been pushed out of the war.

Rebecque of course was also present at that battle as a staff officer, busily oiling the wheels of command and occasionally playing a decisive command role himself, as when he helped rally the broken Dutch militia battalions of Bijlandt's Brigade when they retreated to the position of the steadfast 5th Militia Battalion, which sustained such heavy casualties at Waterloo, only to be maligned by later historians.

During the years the United Kingdom of the Netherlands existed, several complaints were raised by the Belgians towards the regulations of the government.

Rebecque (who was the political antipode of his liberal nephew Benjamin Constant, probably because of his traumatic experience in the Tuileries in 1792) now counseled playing the military card.

He is credited with (or blamed for) having made the plan for the assault on Brussels on 21 September, which ended catastrophically, and caused much bloodshed.

This minor incident got a peculiar follow-up when Eenens (by then a lieutenant-general and military historian), published Documents historiques sur l'origine du royaume de Belgique.

de (1875) Le prince d'Orange et son chef d'état-major pendant la journée du 12 août 1831, d'après des documents inédits, in an attempt to contradict Eenens' accusations.