Beauharnois is a city in the Beauharnois-Salaberry Regional County Municipality of southwestern Quebec, Canada, and is part of the Greater Montreal Area. The city's population as of the Canada 2011 Census was 12,011. It is home to the Beauharnois Hydroelectric Power Station and the Beauharnois Lock of the Saint Lawrence Seaway. 

The Battle of Beauharnois was fought at Beauharnois in 1838 between Lower Canada loyalists and Patriote rebels. 

Katherine Jane "Janie" Ellice (née Balfour; 1813 – 13 April 1864) was a British diarist and artist. She is most remembered for her chronicle and watercolours of a trip to Canada in 1838, where she and her sister were taken prisoner during the Battle of Beauharnois. 

The Battle of Beauharnois was fought on November 10, 1838, between Lower Canada loyalists and Patriote rebels, after 500 armed men had converged on Beauharnois, on November 3–4, overtaking the seigneurial manor.

The seigneury of Beauharnois belonged to the Ellice family, having, in 1796, purchased it from Michel Chartier de Lotbinière, Marquis de Lotbinière. Edward Ellice, private secretary to John Lambton, 1st Earl of Durham, had then been in residence for several months. He and, separately, his wife, Lady Jane Ellice, and her sister, Eglantine "Tina" Balfour, later Ellice, were taken prisoner, along with a number of others. Ellice's watercolours, sketches and diary survived and recorded that they were unharmed.

The town rose following a series of raids by rebel leaders who had escaped into the United States. François-Marie-Thomas Chevalier de Lorimier commanded the ranks of the Patriote rebels. The British were victorious, and 108 rebels were captured and tried in Montreal 58 of the Patriote rebels were deported to Australia, while Lorimier was hanged.

Government forces burned several buildings in the area in reprisal for the rebels’ actions.

Eglise St-Clément




183 chemin St-Louis, Beauharnois