At ARCAT, we found an 1877 letter from the Anglican Diocese of Toronto to Bishop Lynch asking for his support for a day of thanksgiving in November. The campaign must not have been successful, because no days of thanksgiving are recorded as having been observed between 1872 and 1879.
The current date of Thanksgiving was officially fixed in 1957 for the second Monday in October. The reason for the holiday is stated as "For general thanksgiving to Almighty God for the blessings with which the people of Canada have been favoured."
Prior to that, the date was proclaimed each year, and the reason for thanksgiving varied. Many years were thankful for "blessings of an abundant harvest."
Some other thanksgivings of note:
- Thursday, January 10th, 1799: "In signal victory over our enemy and for the manifold and inestimable blessings which our Kingdoms and Provinces have recieved and daily continue to receive."
- Thursday, April 6th, 1815: "End of the war with the United States of America and resotration of the blessings of Peace."
- Wednesday, February 6th, 1833: "Cessation of cholera."
- Monday, April 15th, 1872: "For restoration to health of H.R.H. the Prince of Wales."
- Saturday, August 9th, 1902: "King's Coronation, as a day of General Thanksgiving and rejoicing."