
Military records are primarily used to track the military career of a particular person. The question is where to start. Besides detailing the military history of a particular person, military records can be used in various ways. Wondering why great-great-grandma was widowed? Perhaps her husband was in the militia and lost his life battling for his country. Wondering how your great-great-grand-aunt met her husband? Perhaps he served in the militia with one of her relatives. Wondering why your ancestors abruptly moved? Perhaps the area they were living was under siege, or they were no longer welcome because of their religious or political views. These are some of the type of things you can use Military records for. They may not directly mention your ancestor but they can help build a history of the area in which they lived and the people they knew.
During the 1800's Canadian men between the ages of 16 and 60 were required to serve in the militia at some point in their life, especially during times when Canada (Upper Canada/Canada West) or Britain was involved in military action. The only exceptions were those who were infirm or those that were clergy. Some males were accepted for service if younger than 16 or older than 60 depending upon the need for those able to fight.

To locate your ancestor's military record first identify the time period. Second, identify the area(s) where your ancestor was living during his life.
These two factors (time & area) will help determine which branch of the militia your ancestor would likely belong to. If you don't know where or when the ancestor in question was born, go with the information you do know. For instance, if he married in Lanark County in 1860, check which branches of the militia were stationed in the area at the time. Then check their muster rolls to see if he's listed. You can then track the movement of this militia branch back in time in order to find out when and where he first joined the regiment - likely close to where his family was at that time.

If you have an Ontario military record and would be willing have it used here as an example, please consider sending it in.

There is no shortage of military records for those who served in the Canadian Militia and British Army, the difficulty lies in finding them! Most Canadian military records were kept by the British War Office, but quite a few of these records can be found at the National Archives of Canada. But, there are several other repositories of military information scattered about. If you know the area of Ontario where your ancestor was, or where their regiment was based, check the local resources there (libraries, museums, archives). See the County/District GenWeb for that area for specific information on what is available.
If your ancestor served in the military prior to 1914 the information is public record. For those who served after 1914 the information is covered by the Privacy Act, and can be requested by next-of-kin 20 years after the death of a veteran. To submit a request write to:
Personnel Records Centre
National Archives of Canada
Tunney's Pasture
Ottawa, ON
K1A 0N3
CANADA
If trying to obtain information about an ancestor who served with a British regiment it's best to write to:
War Office and Admiralty
Public Record Office
Ruskin Avenue
Kew, Richmond, Surrey
TW9 4DU
ENGLAND

Not as a whole, no. Those that OntarioGenWeb knows to be online (including the National Archives military database) are linked below.

Cemetery Records
Citizenship/Naturalization Records
Death Records
Funeral Records
Newspapers
Military Actions
United Empire Loyalists: What? Who Were They?
Questions & Answers
Books
Links