From Biographi.ca (by Réal Brisson):

JUCHEREAU DUCHESNAY, ANTOINE, army and militia officer, seigneur, and politician; b. 7 Feb. 1740 in Beauport, near Quebec, son of Antoine Juchereau Duchesnay, seigneur, and Marie-Françoise Chartier de Lotbinière; d. there 15 Dec. 1806.

In 1760 Antoine Juchereau Duchesnay, who was an ensign in the colonial regular troops, was given a difficult reconnaissance mission on the Lake Champlain frontier by Louis-Antoine de Bougainville. After the conquest Duchesnay went over to the service of the British crown. In 1764 Governor Murray* appointed him captain of a corps of Canadians raised to take supplies to the beleaguered garrison of Detroit at the time of Pontiac*’s uprising [see John Bradstreet*].

On 12 Aug. 1765, at Beauport, Duchesnay married Julie-Louise, daughter of Louis Liénard de Beaujeu de Villemonde and Louise-Charlotte Cugnet. In 1767 he entered the business world. The seigneur Michel Chartier* de Lotbinière gave him full responsibility for administering his possessions and properties. That year Duchesnay set up a company with René-Hippolyte Laforce, a ship’s captain, to trade with the West Indies. But it was to the administration of the huge estate left by his father that he would principally direct his efforts. At the latter’s death on 12 June 1772, he inherited the seigneuries of Beauport, Fossembault, Gaudarville, and Saint-Roch-des-Aulnaies. He had the advantage of being sole beneficiary. His older sister, Marie-Catherine, had retired to the convent of the Hôpital Général in Quebec, and for 26,200 livres his brother, Marie-Eustache, made over all his rights of succession to him in order to pursue a military career in France.

From then on Duchesnay worked for himself. He found buyers for the wheat harvested on his estates at Saint-Roch-des-Aulnaies and Beauport. At Gaudarville he farmed out the banal mill and had a new boat built to transport people and goods, for a fee, on the Rivière du Cap-Rouge. He proved a meticulous and thrifty administrator. His estimates for building and repairing mills, houses, and other buildings were very detailed; he did not hesitate to recommend that second-hand materials or tools be used. Accompanied by a notary he travelled over his estates making agreements, principally leases and land grants. Almost all his livestock – dairy cattle and teams of oxen – were leased to habitants at Beauport. By 1774 there were unmistakable signs that the young landowner was living in great comfort. He had several servants working for him. The silverware, linen, jewellery, and various articles of furniture and clothing mentioned in an inventory of his belongings made that year are striking in their quality and value. Jean Garneau, owner of the sub-fief of Duchesnay, rendered him the prestigious homage of his vasselage, which in keeping with custom was performed “bare-headed and kneeling on the ground” before the main doorway of the manor-house. The favourable situation was, however, upset by the partial pillaging of the manor-house and the almost complete loss of the assets of his estate when American soldiers were billeted at Beauport during the invasion in 1775 [see Benedict Arnold; Richard Montgomery*]. In the course of the hostilities Duchesnay volunteered with other Canadian officers for the defence of Fort St Johns (Saint-Jean-sur-Richelieu). He was taken prisoner on 1 Nov. 1775 and spent 18 months as a captive in New England.

Released from American military prison in 1777, Duchesnay immediately went back to work. It was a period of reconstruction. He claimed compensation for the property looted during his imprisonment. He had his mill at Gaudarville rebuilt. At Beauport and Saint-Roch-des-Aulnaies the flour-mills resumed production. Two sawmills were added at Saint-Roch-des-Aulnaies. New storage buildings were erected on his estates. The manor-house was repaired. Large sums had to be invested for transporting wood and materials, importing machinery for grinding and for other purposes in the mills, and hiring skilled labour. Within ten years the seigneur of Beauport became the fourth-largest producer of wheat in the entire province. The unoccupied back sections of his seigneuries of Saint-Roch-des-Aulnaies and Fossembault were divided into lots, which were granted to new settlers or sold when they had reached “some degree of clearing” and had been provided with buildings. Duchesnay did not hesitate, on occasion, to take part of his grantees’ crops in the event of arrears in yearly payments or of other debts; he also resorted to the form of sale called à réméré, which obliged the habitant to repay his debt within a set period on pain of losing his property. A seasoned administrator, in 1782 Duchesnay forced the lessees of the flour-mills on his estates to turn over to him from one-half to two-thirds of the profits from their milling dues; by contrast only one-quarter had been taken 15 years earlier. This revenue, added to the income from the cens et rentes and from maritime trade, enabled Duchesnay the businessman to build up a large fortune.

As a result, he was called upon to supply capital to a large number of habitants, craftsmen, sailors engaged in trading, and prominent citizens. The manor-house served as a credit establishment, and people came from all parts – particularly from the Beauport and Charlesbourg regions, but also from Quebec and Montreal – seeking financial help. In the case of a farm loan the seigneur received the habitant in his manor-house and let him have from 200 to 600 livres in cash, at the legal interest rate of six per cent. Between 10 March 1788 and 6 March 1789 the notary Louis Miray registered no fewer than 18 loans, involving more than 10,500 livres. Duchesnay nevertheless acted with caution. Where borrowers were minors or did not come from his seigneuries, he required a guarantor. If a business loan was involved, he demanded that an account-book be kept, and in the case of a more doubtful debt, he insisted that an object of value be deposited as security.

Duchesnay’s financial situation enabled him to enlarge an already impressive patrimony. Between 1779 and 1809 he purchased five properties, including building sites at Quebec and Montreal and new fiefs. He was concerned to establish his seigneurial privileges by exercising all his rights to the limit. For example, he even required habitants with property on the St Lawrence to take out fishing leases, extending his right of ownership over the water, as it were.

Duchesnay had become a powerful man. He no longer travelled on business. A clerk or steward acting in his name made the rounds of his estates, saw that contracts and leases were put into effect, and collected the various monies due – yearly payments, rents, or even debts. He had innumerable possessions: black servants, a second residence, a fountain and basin of faience in the main room at the manor-house, henceforth termed the “Château de Beauport,” all designed for a spectacular effect. When on 7 May 1778 he married his second wife, Catherine, daughter of Jean-Baptiste Le Comte Dupré, at Saint-Pierre on Île d’Orléans, Duchesnay brought many riches to the joint estate, whereas his 18-year-old wife had as dowry only promises of prospective family inheritances. When he penned his signature he never included a given name: there was only one Juchereau Duchesnay. He had sought verification and confirmation of the titles and letters of nobility devolving upon him from the ennoblement of his ancestor Nicolas Juchereau* de Saint-Denis in 1692. At the age of 52 he was at the height of his renown.

When the House of Assembly was constituted in the summer of 1792 Duchesnay, like many seigneurs from old families and many property owners, cast his eye on political power. He was elected for the riding of Buckingham. In the house he supported the Canadian party on crucial votes, particularly on the choice of a speaker [see Jean-Antoine Panet] and on the question of the assembly’s official language. Duchesnay did not have to be re-elected, for in 1794 he was invited to become a member of the Executive Council.

In the final years of his life this office of executive councillor, which brought no remuneration, seemed to be more and more just a crowning of his career, for he was now an old man and rarely attended the meetings. He neglected his own affairs somewhat: mills and buildings on his seigneuries, including those on his own estate, were in ruins. The many unused and aged sets of harness, sleighs, and calèches that were piled up in his courtyard conjured up an eventful and sumptuous past. He lived in retirement in his manor-house at Beauport, surrounded by his servants. His second wife had left the house in 1794, having been accused of adultery and sued by her husband. Since judge Pierre-Amable De Bonne, a member of the assembly and a colleague of Duchesnay on the Executive Council, was directly implicated, the whole Lower Canadian political world was shaken by this painful affair. Duchesnay’s wife launched an appeal to the highest courts in the colony for a separation as to bed, board, and property and for custody of her children. Her suit was dismissed. Eventually, however, the Duchesnays came to an agreement before a notary: Mme Duchesnay was awarded an annual pension for life and the right to visit her children, who were placed in boarding-schools “for their education.”

Duchesnay’s death in the winter of 1806 did not go unnoticed. The seigneur of Beauport had left a handwritten will specifying the rights, shares, and gifts to go to his heirs, as well as the bonds, promissory notes, and other payments due of which they would be beneficiaries. The registration of the will in a private minute-book in accordance with former French customary law gave rise to a dispute in court when the estate sued John Young for repayment of a debt. The will had not been registered at the office of the clerk of the Court of King’s Bench and the court consequently refused to recognize it as authentic. Nothing further was needed for the traditional struggle between the English party and the Canadian party to move from the House of Assembly to the courtroom. The newspapers of the time, particularly Le Canadien, were full of the matter.

Duchesnay left his family a huge fortune. The 42,000 livres in cash – 30,000 of it in gold coins – listed in the inventory of his property is only one indication of his wealth. The estate to be divided up was substantial. More than 165,000 livres in chattels, as well as the monies due and annual payments in arrears, had to be distributed among the widow and the five children inheriting – two born of his first marriage, Antoine-Louis* and Louise-Françoise, and three of his second, Jean-Baptiste*, Catherine-Henriette, and Michel-Louis*. Only Julie-Marguerite de Saint-Antoine, who was a nun in the Hôpital Général of Quebec, was left nothing under the will. The real estate went partly to his widow, but primarily to his sons; it consisted of the five seigneuries, two fiefs, and a number of pieces of land and building sites, which represented more than 100,000 acres altogether, not to mention the manor-house, houses, and other buildings on the domains. Of the seigneurial properties belonging to Canadians, it brought in the largest revenues, being among the five most lucrative in all of Lower Canada at that period. The few books in Duchesnay’s library, mainly on seigneurial rights and the Coutume de Paris, were just so many tools to serve this resourceful and active administrator. It would, however, take but one generation of heirs to impoverish and break up his immense estate.

From Marianopolis.edu:

Duchesnay, Antoine Juchereau (1740-1806), executive councillor of Lower Canada, was born at Beauport, near Quebec, on February , 7, 1740, the son of Antoine Juchereau Duchesnay, seignior of Beauport, and Marie-Françoise Chartier de Lotbinière. He fought in the Seven Years' War as an ensign in the troupes de la marine; but remained in Canada after the conquest. In 1775 he served against the Americans, was captured, and remained a prisoner of war for eighteen months. From 1792 to 1796 he represented Buckingham in the Legislative Assembly of Lower Canada. In 1794 he was appointed a member of the Executive Council of Lower Canada. He died at Beauport on December 15, 1806. He was twice married, (1) in 1765 to Julie-Louise Liénard de Beaujeu (d. 1773), by whom he had five children, and (2) in 1778 Catherine LeCompte Dupré (d. 1836), by whom he had four children. See P. G. Roy, La famille juchereau Duchesnay (Lévis, 1903).

Source: W. Stewart WALLACE, The Encyclopedia of Canada, Vol. II, Toronto, University Associates of Canada, 1948, 411p., p. 241.