This was really an amazing book although very confusing at times esspecially with the big wordding lmfao but that could just be my problem :). I guess i should state - SPOILERS
But i doubt this is stuff you guys don't already know lol.
Dr. Hasley is a very smart and creative scientist for ONI ( Office of Naval Intelligence ) who played the lead role in the Spartan-11 project. Oddly enough their were Spartans before but they all died. Dr. Hasley would choose 75 kids out of 150 that fit the requirements she needed. She would be interviewing and studying 5-6 years old, one who was John which was the opening scene in the book. After Dr Hasley decided who she wanted she would recruit or in reality abduct and steal these children, which is why this project had to be kept secret for so long.
The children would be brought to the planet Reach for military training. The children would then be trained by Cheif Mendez, and learn about everything needed by AI Deja who was their teacher and in charge of education, they would also go through dangerous surgies to be genetically modified to be more stronger (many would die from the experiments).
The whole point of the Spartan-11 project was to produce elite soldiers through training and augemenatations. The biological augementation process would actually kill about 35 of the 75 soldiers it was indeed the most risky and dangerous step.
The covenant were introduced after the glassed the Planet Harvest. At this point not much of them were known just that they weren't friendly.
Captain Jacob Keys was a war hero who would go down in History during the battle of Sigma Ocatvias IV for a maneuver called the "Keys Loop". Basically in order for the humas to destroy a covenant ship they would have to out number it 4-1. Because the covenant technology was so much better and ahead. Captain Keyes found himself in a situation where he was outnumbered 4-1 by the Covenant which pretty much met it was impossible for him to win. Ontop of that he had no AI on the ship.
What Captain Keyes would then pull off is what would make him famous. He initiated a manever which was nicknamed "The Keyes Loop". Keyes had the ship(Iriquous) go on a direct collision course with a big Coventant ship. So he really was flying right into the ship the was much bigger then his which would obviously lead to his ship blowing up.
While he sent the trip to a way one trip to hell the two other Covenant ships fired plasma missiles, Keyes then turned on the emergency thrusters which accelereated the ship to miss the missles. But the missles had a tracking device of some sort and continued to follow the Iroquos. Captain Keyes then unleashed a nuclear warhead that seemed to have went in the wrong direction.
At the last minute with PERFECT calculations Keyes simply gazed the Covanents ships shield and moved out the way in one piece. With the other Covenant missles left crashing right into the big Covanent ship. Keyes theory if our weapons are not strong enough to take them down we will then hit them with there own weapons. The other two ships then followed the Iroquous. Now that was floating was a million pieces of the big Covanent ship. So Keyes lead the two ships right into the warhead Nuke which the covenant ships couldnt see on there motion sensors because there was millions of pieces of metal. So the nuke activated and blew the two ships up. Leaving the last covenant ship to run.