Siege of Vraks - Azrael's Plan: Achieving orbit outside Vraks' orbital defence laser coverage, the Dark Angels released their cargos of Thunderhawks to enter the atmosphere and fly around the planet to the chosen landing zone at the Srna Flats. Azrael had chosen this area for landing because it was located at the foot of the Abaros Hills directly south of the star port. It only took mere hours for the Dark Angels to unload their forces from orbit.The star port was chosen as the Dark Angels' primary objective for three reasons: one, the star port was the easiest way for off-planet support to reach the defenders. Secondly, a new attack would force the defenders to commit forces against a new threat. There was currently only a small garrison to defend the star port, because it was not directly threatened by the Krieg regiments, and this in turn freed troops for the front line. The Dark Angels would draw the enemy troops into a new battle, and thus thin the lines, which would aid the 88th Siege Army's attacks and help bring about the long awaited breakthrough. Thirdly, and known only to the Dark Angels themselves, and probably the most compelling reason for their quick response, was that there were Traitor Legionaries now on Vraks.These Traitors might have knowledge about the "Fallen". Though Azrael had no proof that any of the Fallen were amongst the defender's new allies, the Inner Circle of the Dark Angels knew the name Arkos well -- a reviled black-hearted Traitor from the ancient days of the Horus Heresy. If Lord Commander Militant Zuehkle could not identify the power amoured forces now facing him, the Dark Angels' Inner Circle knew full well who these warriors were. Azrael had brought along Interrogator-Chaplain Belphegor to extract information from any Traitors he could capture.Azrael's plan of attack was carefully considered. He would launch a fast moving armoured column across the Srna Flats, envelope the star port, and then strike at wherever he felt the enemy was weakest. He could not afford to enter a war of attrition. Taking calculated risks, the Supreme Grand Master was going to commit his battle-brothers to intense street fighting without the aid of the orbital bombardment guns of his battle barge and strike cruisers. His ships would not risk Vraks' defence lasers. Once the attack on the star port was underway, he would attempt to seal off the battle areas from further reinforcements by capturing and destroying the main roads across the Srna Fault line and Balan trench, a set of grand causeways that carried the service roads over great chasms. With these gone no reinforcements could move from the Citadel or the defence lines to assist in the battle at the star port. This task was given to the 3rd Company under Master Orias. Once completed they could move to aid the rest of the strike force already engaged at the star port.The arrival of highly mobile Adeptus Astartes forces created a strategic problem. They could strike anywhere at anytime, simply flying over the defence lines to strike directly at the Citadel itself. Now Arkos' wisdom proved invaluable and correct. The Dark Angels could not risk attacking the Citadel with its defences and garrison fully intact. Still, in order to counter the Space Marines' attack wherever it fell, troops had to be withdrawn from the second defence line and sent to garrison other locations, including the star port. The presence of just 500 Space Marines was already influencing the entire war on Vraks.