Ad Victoriam

Ad Victoriam (sometimes misspelled as Ad Victorium in the game files) is both a quest and achievement/trophy in Fallout 4.

Synopsis
Liberty Prime is finally ready for combat, and the time has come to directly assault the Institute. While the scientists at the Institute feel secure underground, the Brotherhood has plans to deal with that advantage, and turn it into a disadvantage.

Walkthrough

 * 1) After speaking with Proctor Ingram, insert the Beryllium agitator into Liberty Prime, and use the nearby terminal in order to fully activate war machine.
 * 2) Liberty Prime will then need to be escorted through the ruins of Boston, where it will head towards the C.I.T. ruins. Heavy synth resistance is met along the way, although Liberty Prime can handle these threats with no problems. Hang back and collect the loot.
 * 3) Upon reaching the C.I.T. ruins, Liberty Prime will begin making a hole straight down into the hidden depths of the Institute, in which synths will begin teleporting in en masse, and must be dealt with in order for Liberty Prime to proceed.
 * 4) After a breach has been made, drop down into the chaotic scene below.

Behind the scenes
The phrase "ad victoriam" is Latin, meaning "to victory", and is the motto of the Brotherhood of Steel.