Confidant, Father, Defender
Jacob was born and raised on Earth where he spent the better part of his childhood around the Pacific Ocean where he grew to liking books and history. One of the more notable books that Jacob read was one of Elias Carver's theory, but Jacob did not share Elias' views about the Colonies; he thought that Elias was too pessimistic. By reading more and more about other planets, Jacob decided to join the UNSC by enlisting in the Officer Candidate School (OCS) in the beginning of the 26th century.
While in his second year at the OCS, an instructor decided to test his pupils. What happened during the 'test' remains a mystery, but the poorly planned test ended up costing 14 Ensigns their lives and wounding others. Jacob was one of these wounded, and had to spend 2 months in rehabilitation for plasma burns. While in recovery, Jacob was interviewed by his superiors to what had happened. Jacob refused to answer any questions, even when he was threatened with demotion. It is not known what eventually happened to the investigation, but the young Junior Lieutenant was now under close observation. Jacob's refusal to testify is what sparked a young doctor Halsey's interest.
Only 7 weeks since OCS and Jacob was already given the command to the UNSC Magellan. This would not last however, as Dr. Catherine Halsey had used her influence to rescind this order and to send Jacob to her. Since Catherine knew his track record, she knew he could keep a secret, just the kind of person she was looking for. Being in the planning stages of the ORION Project Generation II, she needed someone she could trust to visit and study potential subjects. As the ORION Project was highly classified, Catherine and Jacob pretended to be looking for a nice school for their daughter, as a ruse to visit all the subjects. The very first subject they visited was a young boy, fond of King of the Hill (as he always won), a head taller than his classmates and overall great physique. This subject was to be subject 117, and was later given the name John-117. Not being told the entire story, Jacob started to put all the pieces together and began to suspect the true nature of the Project. As soon as Catherine found out about this, she sent him back to normal duty with a full Lieutenant commission. Even though they were now at a distance, Jacob and Catherine grew closer together, eventually leading to the birth of their daughter Miranda.
Being in 'regular circulation', it did not take long for Jacob to develop a reputation. As the commander of the frigate UNSC Meriwether Lewis during the start of the Human-Covenant war he led a small group of security troops against a Covenant ambush and held the Covenant off long enough for the ship to escape. He sustained a deep gouging plasma burn to his thigh and had his hand shattered, which was later rebuilt. He would later take command of the Stealth frigate UNSC Midsummer Night in which he would garner many citations and years of combat experience. It was only during one of these tours that Jacob had to kill his first human on Charybdis IX during a large riot.
Shortly after this confrontation, Charybdis IX was glassed by the Covenant. The Midsummer Night chased an Insurrectionist freighter, the Kestrel to the Rubble. Jacob took command of the Midsummer Night after his commanding officer Dmitri Zheng was killed by a traitor of the command crew. He later fought in the Battle of the Rubble, saving over a million human survivors from the Rubble. He was promoted to Commander by Preston Cole for this feat. He later taught at the OCS Academy, with several high officials at HIGHCOM thinking he didn't belong in command of anything but a classroom, if that.
Despite this, Jacob found himself in command of the UNSC Iroquois in April 2552 on which he foresaw a Covenant attack on Sigma Octanus IV. The young Ensign William Lovell logged a large gravitational anomaly inside Slipstream Space but dismissing it as Covenant based on its immense size. Jacob noted this anomaly and realised that this large mass was a Covenant Battle Group. Because Slipspace works differently than regular space, and the ships were flying close together, the slipspace radar only saw a large mass without features.
Jacob concluded that the mass consisted of 4 Covenant frigates and commanded enough ships to battle that. However, when the Covenant battle group exited slipspace, the Iroquois found itself outmatched by the arrival of at least 24 ships consisting of at least one DDS-class carrier and one RPV-class light destroyer. Despite the hopeless tactical situation, Jacob resolved to attack. The Iroquois set a collision course for the destroyer at emergency acceleration while launching a nuclear warhead in what seemed to be the wrong direction. The two escorting frigates proceeded to launch a salvo of plasma, but the Iroquois managed to evade by utilizing the emergency thruster. Having missed their target, the plasma came about and continued to track and home in on the Iroquois.
The trailing plasma was to prove critical to the success of Jacob's strategy. A last minute course correction allowed the Iroquois to merely "graze" the destroyer's shields rather than smash directly into the ship properly, resulting in the destruction of a large portion of the Iroquois' armour (he had torn through 2 meters of titanium and had breached every bottom deck of the Iroquois). However, the tracking plasma was unable to correct for the sudden manoeuvre of their target, and in consequence, impacted on the destroyer instead. A heavy salvo of Archer missiles sent the remaining Covenant Warship to its destruction.
With the momentum built up during the first phase, the Iroquois performed a slingshot manoeuvre around the planet. Once safely away, the nuclear warhead deployed earlier, was detonated, completely draining the shields on the two frigates. Having completed its orbit, the Iroquois resumed its attack and destroyed the two frigates with two heavy MAC rounds and hundreds of Archer missiles.
Vital to Victory
Having served the UNSC loyally for years, the decorated Captain was given the very important task of transporting SPARTANs deep into Covenant space to capture a High Prophet to be used as ransom to end the war. Jacob was given the UNSC Pillar of Autumn on Reach for this task, but before the Autumn could leave Reach for slipspace, the Covenant attacked Reach. His mission scrubbed, Jacob offloaded most of the SPARTANs to the surface of the planet and sent 3 to Reach Station Gamma. He then tried to aid in the defence of Reach and even destroyed the supercruiser flagship of the fleet, but ultimately, his efforts were in vain. He could only pick up John-117 along with a wounded Linda-058 and a handful of Marines from the station just in time to flee the pursuing Covenant.
At some point after retrieving John-117, Jacob docked the Pillar of Autumn at the Aszod ship breaking yards while waiting to receive a fragment of Cortana from Noble Six. This fragment held valuable navigation data that would lead the Pillar of Autumn to Halo. Noble Six gave covering fire against a Covenant CCS-class battlecruiser and waves of other Covenant aircraft with a ground-based mass driver as the Autumn took off and withdrew.
Having escaped the Fall of Reach, Cortana would take control of the ship and steer her toward Halo. Here, after John-117 and Cortana left the ship in a life pod, Jacob took manual control and continued to fight the Covenant ships while trying to land on the Halo Array. Jacob and the command crew of the Autumn managed to get aboard a similar life pod and thus escaped the crash landing of the Autumn.
Having landed on the ring, Jacob and his squad tried to reach shelter. During their search, Ensign Ellen Dowski continually pestered Jacob and the rest of the crew by saying that they should surrender to the Covenant. This went on for so long, with emotions flaring so high, that she eventually was tied up and gagged "so she could surrender and be taken prisoner". Later, she was captured by a squad of Sangheili and Unggoy, and while giving her captors information, she betrayed her comrades by identifying her CO, so that she could prove she was right and be taken prisoner along with the others. The Sangheili proceeded to systematically execute everyone in the group, except Captain Keyes. Dowski became shocked at this and was about to protest when the Sangheili shot her in the forehead with her own M6D.
Jacob was taken aboard the Truth and Reconciliation but was later rescued by the group of John-117, ODSTs and Marines. Commandeering a Spirit dropship, Jacob flew everyone to Alpha Base where he assumed command. Together with Avery Johnson, Fire Team Charlie and Second Squad he went to explore what he thought was a Covenant weapons cache. The facility they were investigation turned out to be one of the Halo's Flood containment facilities. Loosed by Covenant intervention, the Flood quickly attacked and overwhelmed Jacob and his squad. During the fighting, a Flood Infection Form took control of Jacob and turned him into a Flood Combat Form. But after realising Jacob's significance to the UNSC, he was merged with several others to make a Proto-Gravemind.
One of the tortures Jacob endured was having his memories ripped away one by one as the Flood tried to learn anything that would help attain new sources of food. The Flood hoped that his intelligence would help them to operate a damaged Covenant cruiser and escape the ring, but Keyes was able to fend it off by constantly accessing data that was permanently stored in his Command Neural Interface, while feeding it those of his memories that were not vital to the survival of humanity, such as his name, age, and service number (though definitely not anything that could lead to the thought of the location of Earth).
However, before Jacob succumbed to the overwhelming pressure, John-117 boarded the ship once again looking for Keyes and found only the Proto-Gravemind form. The Captain was able to contact John three times, warning him to leave him behind, before the Proto-Gravemind fully overwhelmed him. Jacob's life officially ended when John punched through his skull to retrieve his Command Neural Interface after his mind had been absorbed by the Flood infection, with Cortana stating that "she knew that this was what he wanted." His Command Neural Interface enabled John and Cortana to start up the Pillar of Autumn's engines so they could destroy the Halo ring by overloading and exploding the engines.
Your father's actions were in keeping with the highest traditions of military service. His bravery in the face of impossible odds reflects great credit upon himself and the UNSC. The Navy has lost one of its best.