The Parisian Front (also known as the Paris IV Line) was line of defense drawn by the UNSC in the latter stages of the Human-Covenant War. A considerable amount of war materiél was spent in trying to hold that line after the Covenant flooded the Outer Colonies and outermost Inner Colonies following Admiral Cole's presumed death at Psi Serpentis, with the base of operations located on Paris IV. The line fell in 2549, following the Covenant victory at the Siege of Paris IV, allowing the Covenant to make forays deeper into UNSC-controlled space, ever closer to Earth and Reach.