Shut Up and Get Behind Me... Sir Walkthrough - Guide for Halo

Shut Up and Get Behind Me... Sir Walkthrough
Now you'll have to defend the Captain's life as you battle your way out of the ship. 
Immediately, a pair of cloaked Elite will show up and start blasting. Be calm and 
take them out with the Sniper Rifle. Let your attending marines take care of the 
riff raff. When these two drop, move through the doors and start blazing a trail. 
Just follow the trail of enemies. You'll meet a couple of Elite on the path, but 
mostly Grunts and Jackals. Stay out in front of the crew and clean house with 
grenades and the Assault Rifle. The more guys you kill on your own, the less threat 
your Captain will face. 
Eventually, you'll have to battle all the way down the purple hall. Eventually, 
you'll reach the large bay with a circular, central platform. In the distance, 
you'll see a cloaked Elite with a laser sword. Drop him with the Sniper Rifle and 
another will appear. Take him down the same way and step into the room. There will 
be a conversation about how to get out of the ship, and ultimately, Cortana plots a 
way out. 
She gives you a nav point to follow, and at the same time a group of Grunts show up 
to rain on your parade. Spray them down with some Rifle fire, then move through the 
door toward the nav point. Again, run ahead and clear a path. The nav point will 
point you where you need to go. You'll have to run through most of the ship to get 
there, but once you do, all you have to do is push a button to have the dropship 
move down a level and get you and your precious Keyes out of there.