Cortana and the Chief were flying on a Pelican with the rest of the squad when Del Rio came through via holo to give them the orders. He was rigid, as if he was doing all that he could to keep his fear from seeping out. This isn't good.
"Infinity to Gypsy Company. The air corridor to the gravity well is blocked by particle cannons. Infinity's shields are still down. Open the lane for us to move up and provide air support."
"Captain, what's air recon's assessment of the terrain?" John asked.
"I know you've been off the field for a while, Master Chief, but this is a blow through op. Sending in recon would just slow us down," he snapped. "Telemetry indicates that the particle cannons are being controlled from a command post southwest of our position. Neutralize the target and we'll meet you on the other side to take the Gravity Well. Infinity out."

Cortana did what was the equivalent to an eye roll and said via their private communication, "I don't know about you, but I like a little more intel, with my intel."
"We'll make it work," the Chief said.
You always do Chief. No matter how ridiculous or incompetent someone is.

The Pelican landed and Palmer's voice came through The Chief's helmet.
"Chief? Spartan Sarah Palmer in Infinity CIC. Commander Lasky's waiting for you on the Mammoth."
"On our way," he said.

As The Chief came through the clearing they looked up to see what was indeed the Mammoth, a rolling piece of military hardware so large it put a Scarab to shame.
"Well, somebody's overcompensating," she smirked.

They climbed aboard the Mammoth and made their way up to Lasky who was standing out looking over the terrain, his expression grim. "Chief, unfortunately for us we've got to manually bring down a couple of the particle cannons before we can get to the command post."
We would have known that if Del Rio had actually done his job and sent out scouts.
"Understood Commander," the Chief said reassuringly "We'll make it happen."
Lasky seemed to firm up by the Chief's confidence and nodded.
"Chief? Palmer again. The Mammoth's got jetpacks onboard. If I were down there I'd want one."
The Chief chose not to speak, but instead used his acknowledgment light.

Cortana found it interesting that Palmer didn't use her military title when speaking to the Chief.

It wasn't long after the Mammoth rolled out they encountered a large Covenant tactical force with several Ghosts and Wraiths.

"Sir, I see the Covenant forces. Leaving the Mammoth to engage," the Chief said as he exited the vehicle.
"Acknowledged Chief. All Spartan Units, prepare for combat. Chief has tactical command. Lasky out."
"Cortana?"
"Scanning Covenant Battle Net," she said. "Hmm. It looks like just beyond that ridge they have the bulk of their forces underneath protective shields. If we can blow up the main rector core for those it should be enough to destroy most of their equipment."
"Understood," he said.
"This UNSC AI Cortana to Spartan forces. We're on route to this location" she said uploading the coordinates, "to destroy the Covenant's stronghold. Blast anything that comes in our way. Cortana out."

Immediately a Wraith tank spotted her and The Chief and began to make its way towards them firing its main gun. Luckily the Wraith tanks were slow, and though the main weapon was powerful, also slow. The Chief unclipped a grenade and began running at full speed towards the tank, dodging the main gun. He jumped, climbed aboard the tank, threw a grenade inside and then dismounted before it exploded.
Ha. Let's see the Spartan IV's try and top that!
Cortana. It's not a competition.
Oh, hell yes it is.
Try to act more professional.
Tell that Del Rio.
Cortana!
What is Spartan unit Jackhammer even doing right now?
Looks like they can't take a tank by themselves.
Cortana….
Why don't you concentrate on what you do best, helping the Chief?
I'd much rather be condescending.
At least we're honest.

"Chief! Ghost inbound behind you," she said suddenly paying attention to her scanners.
"Tell me when."

Cortana watched the ghost carefully as the Chief moved forward, feigning ignorance. Just a little closer…. "Now!" She yelled.

He back flipped into the air landing on Ghost and knocking the Elite out of the driver's seat. The Chief grabbed the controls, using the back end of the Ghost to slam into the Elite killing him on contact. With a Ghost, the Chief was able to disable another Wraith tank before boosting up the side of a steep hill going behind enemy lines to where their staging ground was. Cortana could see two main shield generators.
Good she thought. Two explosions from those generators will take out this section of the mountain.

The Chief wasted no time. He began to accelerate the ghost towards the first generator at a frightening speed, ignoring the Covenant on either side who were shooting at them. He drove the Ghost into the shield towards the generator and just before it hit did a back flip off the Ghost. In midair he used his jet pack thrusters to propel himself toward the second generator barely clearing the blast which took out a chunk of the Covenant's supplies. He then reached for another grenade, his thumb ready to arm it. Once he fell through the second shield he tossed the Grenade and ran as fast as he could. The blast triggered another explosion of one of the Covenant's reactor cores sending her and the Chief flying in the air.

"That was close," Cortana remarked.
"I had it under control."
"That was…slightly impressive," she said teasing him.
He allowed himself an amused grunt to her remark.
"Chief to Lasky. Area is now secure."
"Understood Chief. Mammoth's moved slightly down from our original position but we'll wait for you to catch up."
"Not necessary Sir. I can catch the Mammoth."
There was a momentary pause and then, "Understood. See you when you get on board."