The Immelmann is essentially a maneuver for repositioning. Not to be confused with it's WWI namesake, its main value lies in enabling the fighter to reposition at any angle with almost no lateral displacement.
A pair working as a team is much more effective than two fighters working individually. They guard each other's visual blind spots and, as illustrated in the Attack Section, hunt as a co-ordinated unit. The wide spacing is dictated by two factors: the long reach of contemporary weaponry, and the large amounts of sky needed for maneuver at high subsonic or transonic speeds. There are few set maneuvers for the pair; just a few general tricks to meet certain situations, as follows.
Back in 1916 the original Immelmann turn was more akin to the vertical reverse than its present-day counterpart. The modern version of the Immelmann is a vertical climb or half loop, possibly aileron-turning during the climb, then rolling out into level flight at the top. Its main value lies in using the vertical plane to change the direction of flight in the smallest possible horizontal space. Horizontal turns at normal fighting speeds take up a lot of room laterally. Using the vertical plane enables the fighter to turn square corners in relation to its position above the ground. This maneuver makes repositioning for a further attack, or to meet a threat, much easier than would be the case using horizontal maneuver only.