A strategy is an overall plan of a series of smaller connected actions intended to achieve a greater goal or objective.
In military terms an overall campaign plan would be a strategy. A plan for winning a war would be a strategy where as the manoeuvring of a unit on the ground would be tactics.
Civilians can have strategies as well although these tend to have more of a Cake and Arse Party feel about them than efficient achievement of the goal. This is usually due to inefficient tactics used.
Gulf War 1 (Military): The liberation of Kuwait, the crushing of the Iraqi armed forces as a threat and removing Saddam Hussein from power. Result? Kuwait liberated, Iraqi army shattered ... and then the politicians intervened. Frightened by the brutal efficiency of the military strategy and shocked public opinion, they terminated the strategy before it was completed.
War on Knife Crime (Civilian): Government strategy to deal with knife crime. Strategy ineffectual by being too soft on knife carriers (only 1% end up in jail), sentences not a deterrent and too many excuses made for criminals by Social Workers. Result? Knife crime continues to soar, teens carry knives as a matter of course and teenage murders are at epidemic levels.
A good visual depiction of strategy can be found here