The tackle should usually play right up to the line, on the defense. Sometimes with a very quick opponent, it may be better to play a little back from the line. He should be restless, and on the alert for an opportunity to go through on the side of his opponent offering the best advantage. He should watch the ball closely and spring the instant it is snapped. His course of action in reference to his opponent must be to get him out of the way as quickly as possible. It may often be best for the tackle simply to drive his opponent back with hard, quick pushes. This might frequently be best when the play is between him and the guard, because the time for preparation to tackle is exceedingly short before the runner will be going past, and the whole attention must be given to securing a momentary freedom from interference, for a quick spring. The tackle has a great deal of this quick tackling to do because the runs are so frequently made in his region. Much of this also must be done right in the midst of interference, when the only chance to get the runner is by hurling himself headlong at him as he passes.

On end plays the tackle must break away from his opponent as quickly as possible. He will have no time then to carry his man before him except, perhaps for an instant, as he pushes him back to get by him. Yet he must make sure to knock his opponent sufficiently off his balance to prevent his following him and giving him a shove at a critical moment. In defense on an end play, everything depends on the tackle reaching the runner before he begins to turn in order to circle the end, and before he has swung in closely behind his interference. The runner then has not yet gotten under full speed and the interferers are somewhat scattered and looking toward the end. The tackle has the best chance for defeating end runs; in this he is ably seconded by the end man, the two working together, in fine team play.

The tackle must go through the line on the defense. The plan of waiting until it is seen where the run will be made and then running behind his line to help, if the play appears to be on the other side, is disastrous to a good defensive game. It not only is dangerous, because it leaves the way clear for a splendid run on a double pass, but it is also especially harmful because it gets the tackle into the habit of waiting for every play to become well started, and this is fatal to a strong defense. If the play is around the other end, the tackle should follow the runner around and try to overtake him. It is sometimes possible for a fast runner to do this when he breaks through quickly. In following the man with the ball, the tackle must be on the watch constantly for a double pass. If he suspects one is to be made, he must be sure not to be drawn in or blocked as he runs behind the line. It would be better, in that case, to go straight through. The tackle can do more to defeat a double pass than any other player, for, if he plays his position well, he will meet the runner when there is not more than one inter-ferer to combat. If he then does not tackle the runner, he can force him to run so far back of the line that the rest of the team will be able to come to his assistance before he circles the end.

When the opponents are going to kick, the tackle has an especial burden resting on him because he is in a very advantageous position for breaking through quickly and stopping the ball. No other rusher should reach the fullback so quickly, unless, perhaps, the guard, because none other is so well placed and at the same time interfered with so little.

He should, therefore, go through with all his strength and speed, and jump high in the air to stop the ball. His hands should be raised at the same time in order to place as high an obstacle in the way of the ball as is possible. The tackle on the same side as the kicking foot has a better chance to stop the ball than his companion on the other side, and he must, therefore, put forth his utmost efforts. Frequently, the tackle, like the guards and center, can work some clever team play in conjunction with an extra man, whereby one or the other can go through the line with little opposition.

There are a variety of tactics which can be employed in getting through the line, and every tackle should be able to use them at will. Those are best which enable the tackle to get through quickly and at the same time permit him to watch the runner closely. This is a point which ought to be deeply impressed on the minds of all the rushers. The situation changes so quickly when a run is being made that it is not safe to have the eyes off the runner for a second. The methods usually employed in breaking through the line are : striking the opponent in the chest quickly and hard, and following it up with a shove to one side when he is off his balance; whirling suddenly around him, using either foot as a pivot; ducking quickly to one side; making a feint to go one side and going the other; striking the opponent with the head or shoulder and lifting him aside; stepping a little to one side as the opponent comes forward and swinging him through behind him. The tackle can sometimes secure an advantage for breaking through by pushing his opponent back from the line just before the ball is snapped. He must be very free to move, and go through with a jump. It is better to keep as low down as possible in doing this.

The position which the tackle should take on the defense against mass plays from the center of the field is shown in the diagrams further on. He should move off from the guard sufficiently to protect the side of the field and at the same time be able to spring back close to him on any play directly forward. It is his special duty to tackle the runner if he comes out at the side of the formation. In case the runner does not come out before the opposing rushers meet, the tackle should dive in and secure him, if possible, but in doing this he must be careful not to leave too great a space between himself and the guard, as an opening through which to send the runner may be intended at that very point.

It is impossible to lay down rules of action for the tackle on wedge plays in the line. He must work according to his best judgment based on the situation; but an important factor in successful play will be to put in the work low down. If he is caught by the wedge in an upright, or nearly upright position, he will be rendered absolutely useless. For this reason, it is often best to dive in at the side of the wedge about knee high and try to tackle the runner, or cause him to fall over him. If the wedge is revolving, it is often best for the tackle to fall down in front of it. The tackle must consider it his first duty to assist the center and guards in checking the wedge, and leave the other players to attend to the runner if he comes out from behind or at the side.

On the offense, the tackle cannot leave any unprotected space between himself and the guard, if it be occupied by an opponent. He must therefore always take the inside man. This may require him to play close to the guard. From this position he must do all his running with the ball, all his blocking, all his interference for the runners, and make all his openings; varying his attitude toward his opponent to meet the special need of the moment. In making his opening the tackle has to outwit and combat a very free opponent, one who, as a rule, is constantly changing his position. This renders it difficult, sometimes, to make an opening because frequently it has to be done while the opponent is changing his position, and when, perhaps, the tackle himself is not in a favorable position for making that particular opening. Likewise, when trying to block his opponent, the tackle must follow him closely and keep in front of him, and must be all on tiptoe to dart forward to get in a body check before the opponent acts.

When the tackle runs with the ball or moves away from his position to accompany the runner, he is much more at liberty in choosing his place in the line. His great aim should be to take a position which should not be noticeable by its strong contrast to previous ones, and yet, at the same time, be one which he can use to the greatest advantage in the play in hand. Usually that position should be up in the line not more than two or three feet from the guard, but sometimes it is better to stand a little behind the line.

It is most important to the tackle when he runs with the ball that he get away from his opponent with the utmost quickness, and then, that he run with tremendous speed and power. The secret of successful running from any position lies in this. The practice given to improving in this particular should be faithful and constant. The run of the tackle cannot be successful until there is added to the quick start and strong headway, such training in taking his course that he will neither run too near the line, nor too far back from it; and the ability to circle around the quarter-back and take the ball from him without a diminution in speed, and then plunge into his opening with a force which cannot be stopped short of several yards. Much depends on the course taken. The tackle's failure in running often results from slowing up to turn into the right opening and thus losing his power. Instructions in running and holding the ball are given in the chapter on the half-back and full-back.