Is there a single word for reasoned action?

Solution 1:

Stratagem:

an artifice or trick in war for deceiving and outwitting the enemy.

(Source: Merriam-Webster)

Solution 2:

Strategy

A careful plan or method.

Another option:

Gambit

A planned series of moves at the open of a chess game

A calculated remark intended to start a conversation or make a point

A calculated move

(Definitions from Merriam Webster)

Edit: adding another

Rout

An overwhelming defeat - or to defeat overwhelmingly