Bros to the Close
Bros to the Close is an achievement in Halo 4. It is awarded for making it through the fourth campaign level, Infinity, without a preventable death of a Marine, on Heroic or harder. This achievement is worth 20 gamerscore. Bros to the Close is represented by three fists touching each other to create a star in the centre.
Even though this achievement may be accomplished on solo, it is highly recommended to attempt it on Cooperative Play. Bros to the Close requires the player to have six Marines alive before heading through the door that leads to the landing zone. It is also recommended to keep the Promethean Vision armor ability acquired earlier in the level, so one could count the number of Marines with ease. After the mid-level cutscene ends, the player will have two Marines with them. Arm the DMR-wielding Marine with a Lightrifle, and move on. Once given the chance to pick up another Lightrifle, trade it with the second Marine, who is wielding an Assault rifle. Stay alert and take out any Prometheans in this order: Watchers → Knights → Crawlers.
At one point, Commander Lasky will inform John-117 that there is a squad of Marines pinned down nearby. This squad is composed of four Marines: One of them is wielding a Pistol, another wielding the DMR, and the last two are using Assault rifles. Immediately trade a Lightrifle with the Pistol-wielding Marine, followed by picking up a Railgun and trading it with the DMR-wielding Marine. When heading up to the hilltop, there will be a Promethean Knight who will teleport closer to the player. Use the shotgun or Scattershot if provided, but throwing a frag grenade near its teleportation destination suffices as well. If the grenade didn't kill the Knight, find cover and fire at the Watchers, who will be constructing Forerunner beam turrets. These turrets should be the second priority; the Watchers being the first. After eliminating the Watchers, destroy the turrets since these are the main threat to the Marines as well as the players themselves. Once the turrets are destroyed, return attention to the Knights. The Marines will usually take care of the Crawlers and assist in killing the Knights, but don't expect them to destroy the Knights by themselves.
After clearing the hilltop, arm the Marines with Lightrifles and Railguns, as this will increase the damage they inflict on the enemy. After uploading Cortana to the console, mount the turret on the middle. All the Prometheans will usually charge up the door and ignore the turret to the left. Once again, put the Watchers on first priority, followed by the Knights, and finally the Crawlers. Keep an eye on the motion tracker and watch for any Prometheans that get too close to the Marines. Eventually, the waves of Prometheans will run out, and the achievement notification will appear once the player heads for the door.
On Cooperative Play, it is recommended to have one player focus on the Watchers and turrets, while the other is tasked with eliminating Knights and watching for Marine deaths. During the hilltop section, have one player on the turret while the other stands on the right side of the hill to flank the enemy.