The position of tackle is the most important one on the rush line. The tackle is the "work horse" of the eleven. He is called upon to stop most of the plays of the opponents, since nine-tenths of their attack is aimed at his position or just outside of him. On offense, in the various "tackle-back" or "tackle-over" plays that are so extensively used in the present development of the game, he is required to head the interference or to plunge through the line with the ball like a full back. He has become the important man in every play, and success and failure depend on how he performs his duties. To do all that is required of him, a tackle must have the speed of an end and the aggressiveness and all-round ability of a good back. It is needless to say that he must have courage, weight, strength and wonderful endurance to fulfil the requirements of his position.

The tackle's work on offense is indeed varied. When called behind the line he is used to lead the interference through the line, being, in reality, the "roadmaker" who plows clear the track along which the runner follows. On the plays around the end he leads the interference and is expected to prevent the opposing tackle and the defensive half back from stopping the play behind the line of scrimmage, thus giving the rest of the interference and the run-'ner a chance to get out and beyond the opposing tackle. Then, again, he is called upon to take the full back or half back position to carry the ball through the line on a short cross-buck through or just outside the opposing tackle. The tackle is rarely used to run from his position in the line, as the play is a very poor one on a slippery, muddy field, such as is usually encountered in the month of November, when the important games are played. He may also be required to go over on the other side of his own line to take a position beside his own tackle, there to perform the duties of an end in boxing the opposing tackle, leaving the end whose place he has taken free to care for the defensive half back. The tackle's work when the point of attack is on his own side, inside or outside of him, requires that he shall block or box his opposing tackle long and successfully, until the play can be carried by.

It is very important that the tackle should have mastered the fundamental principles of blocking, breaking through, starting, carrying the ball and interfering, as given in a previous chapter. These principles he must have practiced until they have become a very part of his own make-up and can be performed practically without thought.

He and the end must learn to work together in boxing an opposing tackle or in opening holes through the opposing line. The tackle must always remember that he is responsible for the hole or opening between himself and his own guard. He must also remember that it is his duty to block the inside man of the opposing line, for often the opposing guard moves out very wide or one of the enemy's backs takes a position in the opposing line inside of tackle. This player then becomes the inside man and should be taken care of by the tackle, who should let his own end care for the opposing tackle.

A very important part of the tackle's work is on the defense, where he should exemplify everything that his name implies. He should tackle all the time and all over the field. He should break through and tackle behind the line, and should never be denied. He must not expect anyone else to make the tackle or stop the play. He must not let the runner get outside of his position, for that part of the field is protected only by the end.

The tackle must play low. If he is caught "up in the air" it is impossible for him to stop a hostile play short of a good gain. He must remember to play low, block low, charge low and tackle low. If the point of attack is directly at his position he must hit the interference not much above the knee. A mass play is not hard to stop if it is taken low. On the other hand it is almost impossible to stop if met by a tackier who stands erect.

The tackle should be an expert in the use of the stiff arm, so that he can keep the opposing tackle and end away from him and go through the line. The opposing end is the most dangerous man the tackle has before him, and this man should be carefully watched. The tackle must not in any circumstances permit himself to be boxed, and should nearly always break through the opposing line on the outside of his opponent. He should observe at the very outset of the game the methods which the opposing end and tackle use in blocking him, and, after taking in the situation thoroughly, he should adapt his style of play and mode of breaking through to the situation, so that he can frustrate the plans of his opponents. He and his defensive half back should have an understanding whereby they may sometimes shift positions just before the ball is put into play, thus enabling one or the other of them to get through and behind the opponents' line almost on the instant the play is started.

The tackle should watch the opposing backs very carefully, as he can often tell, by some movement or expression before the play is started, where it is to hit the line, and so be greatly helped in the endeavor to stop it. He must keep his eyes on the ball and break through the instant it is put into play, for it is much easier to break up a play before it is started, than after it has attained its full momentum. The tackle should never run behind his own line but should always go through the opponents' line, stopping the play from behind, if possible, and always watching out for criss-crosses, delayed passes and other trick plays. The tackle will not be easily fooled if he keeps his eyes on the ball. No forward should ever close his eyes in breaking through an opposing line or stopping a play.

When his own side is attempting a kick, the left tackle should leave his position and go straight down the field under the punt. He should go through on the inside of the defensive tackle, giving him a slight body check as he goes by. The tackle on the side of the kicker's leg must block longer but not too long, and should go down fast to stop the runner, in case he has not already been downed.

When the opposing side is going to kick, the two tackles should spread out on the line in the way that will best enable them to get through and block the kick. The tackle should take care and satisfy himself that the kick is not a fake, which may result in a play coming through the line inside of tackle or, more likely, since the full back may carry the ball on a direct pass beyond the line of scrimmage, around the end. The tackle should always go through hard and fast, using his hands to ward off the men protecting the kicker. He should then spring, with arms extended, high in the air in front of the kicker and try to block the kick, which he can often do. If he cannot block the kick, he can often compel the punter to kick almost straight up.

When a kick is blocked there is great opportunity for a touchdown. If the ball is bounding and can consequently be easily picked up, the tackle can frequently snatch it up and race on over the goal line. Sometimes he can kick the ball forward along the ground until it is kicked in goal, where he can fall on it for a touchdown.

The result of every game will depend largely on the strength of the two tackles. They are the men occupying the positions enabling them to stop all runs intended to go out beyond them, and they must be instrumental as well in stopping line plays. The tackle should use his head and should never be caught twice in the same manner by a trick of an opponent. He should be versatile and adapt himself to the situation.

"Be up and doing" should be the tackle's motto.