Originally introduced in a military context, operations research applied quantitative methods, especially of statistics, to developing optimal solutions to challenges in military operations. While it is usually described as having started in WWII, the Canadian Army approach to counterbattery in the First World War may well have been a first application. Some of the early areas of concentration, in the Second World War, were anti-submarine warfare and the aiming of anti-aircraft artillery.
As the field developed, it began to introduce methods from other quantitative fields, and develop its own toolkit.  Optimization techniques were key, coming from mathematics, economics, game theory. Extensive use was made of techniques such as linear programming, nonlinear programming and dynamic programming.
- JS Finan and WJ Hurley (1997), "McNaughton and Canadian operational research at Vimy", Journal of the Operational Research Society 45: 10-14
- Simon Goerger (20-22 February 2007), Tutorial Report: Equipping the Analysis Toolkit, Military Operations Research Society