17 Hours
Note: I do not own Warhammer 40,000 so don't sue me please.
Prelude-On Imperial ship "Emperor's Hammer" (0 hundred hours Sol Time):
Senior Officer Leon Mclane surveyed the drop site with a mix of interest and apprehension. He knew that the planet was under assault by tyranids at that very moment and that he had to make his decision fast, before he was spotted. His orders were quite clear. He and his force (consisting of: 30 storm troopers, which divided into 3 squads each of which were lead by one of his most respected officers, his 2 Leman Russ conquerors, his force of 40 standard imperial guards men, all of whom were from the Steel Legion which had fought on Armageddon, and finally his trusted second in command who would be leading his platoon of Steel Legion troops into battle, Lt. Seluns.) to reinforce a small facility located near a mountain range in the more savanna like part of the planet. This facility was very important to repelling the invasion. This facility Mclane had learned was one of the main missile defense stations, he knew this facility had to be defended. He hesitated for only a second before ordering the drop.
Hour one-Surface of Valnes III near defense facility (1 hundred hours Sol Time):
As the troops and 2 conquerors unloaded from the drop ships, Mclane looked around. He just could vaguely see the facility, protected by mountains on 3 sides. It took half of an hour to reach the point, and when the force finally arrived they were greeted by the commander in charge of the facility, David Lounsairen.
"Very good to see you sir." He said. "Our crew of 12 is waiting inside we have sleeping quarters for all your troops and hot meals for all." Lounsairen beamed. Mclane smiled and stepped inside the heavily reinforced door. As soon as he came in he heard: "Sir we have a large Tyranid force closing on our position fast, we need our defenses ready of the double!" Mclane swore and turned around. The facility was protected on 3 sides by mountains and on its one open more vulnerable side lay a lake approximately 20ft. deep, a massive wall made out of reinforced concrete, with a large gate in the center which was connection to a bridge crossing the span of the lake. Mclane stationed his 2 conquerors slightly farther back near the two flanks of the facility, facing the lake ready to storm up when needed to reinforce the gate. His 4 squads of Steel Legion troops were placed on the large castle-like walls surrounding facility. His 3 storm trooper squads were standing by on more level parts of the two mountains on either flank, prepared to pick off the tryanids one by one from their high spot. Mclane and Lt. Seluns were stationed inside of the main facility ready to give orders and redirect fire using a number of radios, and hidden surveillance cameras. They were ready, and would fight to the last man.