Orbit was also the second phase in a planetary assault and covered the gaining control of the orbital space around the target planetary system and the strategic orbital placement of the units in the invasion fleet.
Two types of orbital assault
Objective orbit consisted in placing the entire invasion fleet in the space above one single objective like a capital or a starport. This would allow the invasion fleet to target key points while remaining safe from raids by small groups of defending ships, but also only allowed for the control of smaller areas. Moreover, this strategy did not allow the invasion fleet to control enemy supply lines. One strategy to reduce the number of objectives was simply to bombard cities and starports as well as industrial facilities.
In a siege orbit, the units in the fleet are placed around the planet so as to prevent enemy ships from leaving and entering. Siege orbits thus reduced the number of logistic assets of the defenders and also allowed for the bombardment of enemy ground forces wherever they would concentrate.
Unther considered this a more risky alternative to the objective orbit, and argued that the orbital siege at the Battle of Hoth was an example of the weaknesses of siege orbits as Darth Vader's invasion force were somewhat handicapped due to Admiral Ozzel's mistake during the approach phase. Because the fleet came out of hyperspace too close to the Hoth system, the fleet units had to rush to get to their assigned positions, giving them little time for deploying fighter escorts. Several Rebel ships managed to escape the system before Imperial vessels had reached their planetary orbital positions.
An important aspect of this phase was, according to Unther, knowledge of the defending forces, as there were several different ways to defend a system from planetary assault. The unorthodox strategies of Carigan at the Battle of Bryx caused severe problems for the Imperial invasion fleet. The most common type of planetary defense, however, was the starfighter-based space-snipe strategy.