GW Download

The mission General's war can be downloaded from here or from steam workshop

(The steam workshop page is updated more often.)

(non-steam) install instructions:

Copy the .pbo file to missions folder in your arma 3 installation folder.

Optional addons:

plpmarkers (highly recommended)
Download:
steam workshop (http://steamcommunity.com/sharedfiles/filedetails/?id=495275491)
or
armaholic: (http://www.armaholic.com/page.php?id=29190) 

UnderSiege Patches and Insignias
(Will show Insignia on the shoulder of special forces)

http://www.armaholic.com/page.php?id=26519

Apex

Currently this mission is compatible with Apex but does not require it.

Arma helicopters and marksman DLC are used in this mission.