How do you use defense break in assassins creed

It's pretty easy(took me a few times to realize),basicaly when they say step forward you hit x(like when your scaling buildings and such but no r1 just x)and right after hit square/box.
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This is a pretty old topic so I am just improving the already given answer. The answer above makes no sense to me so I am going to assume that they are probably using playstation. My answer is for 360 users. First off I would like to clarify that it is not you who are confused with how to perform a defense break but rather the person that wrote the description of how to perform said defense break in the tutorial practice rink. You do not step and hit X(blue button).
**This is how you really do it.
1. Lock onto target with Left Trigger
2. Tap(do not hold) movement joystick any direction you please(It doesn't matter where the enemy is as long as you are locked on).
3. Right after tapping the joystick hit the A button then immediately hit the X button.
-That's how you perform the defense break in the tutorial rink(to receive the trainers "perfect", "the work of a master", and the "that my students is how we all should fight" confirmation.
**When fighting in the field you won't want to just tap the joystick. You'll want to hold it in the direction of the enemy and follow Joystick direction/A button/X button--> with another tap to the X button to actually strike your opponent. This move is best used on Templars and the guards with the helmets as they are prone to blocking 75% of your attacks. Combine this move with the other moves you have learned and you'll be a stylish killing machine.