For four days, November 10 - 13 Findmypast is offering free access to 70 million military records, mostly from the US (including Canada!) and the UK,
Findmypast military specialist, Paul Nixon will present a webinar on Friday 11 November at 11am EST, 4pm GMT, showing how to piece together British Army ancestors’ life stories using old photographs and Findmypast records. Register here.
Don't overlook original records that are always free, such as these from Library and Archives Canada.
UPDATE: Ancestry.co.uk is providing free access to their UK military records, with registration, from 11-13 November 2016.
ADDITIONAL UPDATE: Ancestry.ca has now come aboard with free access to military records, with registration, until end of day 13 November.