The Swiss and Irish troops in French service generally wore red uniforms. When the régiment suisse de Karrer was raised for service in the French colonies by the Ministère de la Marine in 1719, it followed this tradition. This is the uniform worn by the unit when it was first posted to Louisbourg in 1722.
As in all the Swiss regiments in the service of France, the drummers wore the colours of their colonel's livery (blue and yellow in this case). Swiss regimental drums were generally decorated with a flame design of the same colour as the regimental flag. The 1744 garrison mutiny at Louisbourg began when the drummers of the régiment suisse de Karrer began beating 'The Assembly' at dawn. Reconstruction by Francis Back. Reconstruction by Michel Pétard. (chgh.gc.ca)
This man of the Compagnies franches de la Marine wears the grey-white coat of France with the blue facings of the Troupes de la Marine. He is armed with a musket, sword and bayonet. Note the anchor decorating his cartridge pouch. This was appropriate given that these troops belonged to the Ministère de la Marine, which was responsible for the navy as well as for France's colonies. This is how the men of the Compagnies franches would appear on parade or in garrison in one of the larger forts. Reconstruction by Michel Pétard.
The New England Artillery failed to make much of a breech here. The French simply shot them down.
British Marines, 1740s. Detachments from ten British marine regiments took part in the capture of Louisbourg in 1745. These elite troops wore mitres with rounded tops on their heads. (cmhg.gc.ca)
Militia from New England, supported by the British Navy, land at Louisbourg in May 1745. After a short siege lasting 48 days, the French defenders surrendered the fortress. (National Archives of Canada)