Uplinks are the lifeblood of any army in EndWar. They are used as objectives in conquest mode, and they also have bonuses such as air support that can be used once they are upgraded.
Capturing an uplink provides a player with 4 command points, while the powerful mission supports they allow can bring victory. Conversely the more uplinks a player has, the more ground that they have to defend. uplinks can be crashed, or just have their bonuses eliminated through destruction. Uplinks are surrounded by walls that provide good cover to infantry, and can only be captured by engineers or riflemen.
Canonically, the uplinks are connected to the SLAMS system in orbit, and serve to intercept high-danger airborne threats such as ICBMs and strike fighters, thus making it necessary to take control of them to create a "hole" in the shield to allow for these supports. Once an uplink site is held by a power, that region is protected by the shield. When launching an attack, the attacker will bring the uplink system offline, giving a window of opportunity for their special forces to seize the site and turn it to their control, facing resistance from the defending power.
Accordingly, as a power "reboots" uplinks by accessing and conquering them, that power has access to one of several mission supports such as air strikes and EMPs. By conquering additional uplinks, they can boost the signal output from the site and call in more powerful attacks without risk of being intercepted by the missile shield. This makes uplinks critical not only for conquest, but also for assault and siege, as they allow for off-map supports in addition to crediting the conqueror with command points, which they can use to call in supports or reinforcements at a faster rate.