Et Sans Resultat! Essential Player's Guide
Et Sans Resultat! is a set of Napoleonic table top wargames rules from The Wargaming Company LLC.
It is aimed at Corps level and above. While the smallest unit on the table is a battalion or squadron, combat and movement is resolved around the larger divisional organisation. This introduces greater elements of command and control (which make for much more interesting wargaming in my view) and encourages Commanders to worry more about reserves and the coherent deployment of divisions rather than the precise angle of deployment of a battalion in line.
The Essential Player's guide includes the basic overview of the rules, along with a detailed set of explanations of each part of the rules mechanics. This is the basic rule set that you need to play the game.