The regimental depot of the 101st Infantry was the Caserne de Billy in Dreux (Eure-et-Loir). Since it was quite close to Paris, Dreux had always been a garrison town. In 1736, a new barracks was built in the then rue d'Orisson (now the rue d'Orfeuil) to house the men of the brigade de corps du roi.
The building remained in use throughout the Napoleonic wars, but by the 1840s it had become cramped and was in need of repair. It was decided to construct a new barracks, on the plateau to the north of the town, and construction began in October 1845.
The barracks was named after a local man, General Jean Louis de Billy (1763-1806). When the Revolution broke out, he was an artillery instructor at a military academy in Paris. He joined the National Guard, and subsequently served with the Armée des Côtes de l'Océan and the Armée du Rhin, and was wounded at Zürich (2 June 1799). He was subsequently promoted to brigadier and commanded a brigade in Oudinot's Division (III Corps) at Austerlitz. He was killed at the head of his men at the victory over the Prussians at Auerstadt, 14 October 1806.
The barracks would become the home not only of the 101st, but also the reserve regiment, the 301st, and of the local territorial regiment, the 29th. In 1895, a company of the all-volunteer 300th Infantry, 333 men strong under a Captain Immelin, left from here for the campaign in Madagascar.
From 1932, it became the home of three squadrons of gardes mobiles (part of the gendarmerie), as well as a number of colonial regiments. In 1936, it was the home of the 1st Colonial Infantry Regiment. In 1939, the 3rd group of squadrons of 1st Algerian Spahis maintained a presence there, but by that time many of the buildings had been turned over to civilian use.
After the war, the site was progressively taken back into military use, and a number of units, including gendarmerie, were stationed there, including the 1st Colonials between 1948 and 1955. The last Army unit to occupy the barracks was 22nd Colonial Infantry, who left in 1963.
The site is currently occupied by a gendarmerie unit, Escadron 43/3 of the Gendarmerie mobile (responsible for the maintenance of wider public order, rather than for ordinary rural policing). Footage of the squadron's fiftieth anniversary parade in 2011 is on YouTube here. On the same occasion, the barracks was renamed as the Caserne Albert Bertrand, in honour of a gendarme who died in the line of duty in Paris in 1958.
The barracks (which, despite their age, are not protected as historic buildings) and the neighbouring park are the subject of some controversy. They were recently handed over to the departement by central government. Part of the area was subsequently rezoned for housing, which has got a considerable number of people up in arms at the 'threat' to the site. The onside view, which emphasises the barracks as the new home for the departemental archives, is here; the offside view, which emphasises the modern threat to some of the few old buildings left in a town that was heavily modernised in the 1960s and 1970s, is here.
Illustrations: postcards of the barracks from notrefamille; the portrait of de Billy from Dreux par Pierloum; the 1933 aerial view from geoportail. The pictures of Saint-Cloud from delcampe.com and avsaintcloud.com