Remove the Defender
How to spot it: identify the lone defender of a mate square or a valuable piece, then take it: even at a cost, if the thing behind it is worth more. Closely related to deflection (chase it away) and overloading (give it too much to guard).
How to recognise it in a game
Identify what prevents your intended tactic. If one enemy piece alone protects the target or the key square, examine every capture, exchange and forcing attack against that defender.
The common calculation mistake
Removing a defender only works when the follow-up is concrete. Count the material over the whole sequence and check for a replacement defender that appears after the first exchange.
How to defend against it
Use overlapping protection for critical pieces and mating squares. If one defender carries too much responsibility, simplify the attacker's pieces or move the defended target before the defender is forced away.
Now spot it yourself
A real position: find the move. This is exactly what the drills in the app do, banded from beginner to expert.
How this lesson is made: this public explanation comes from the authored Strong Squares curriculum. Automated checks protect its chess data, source fields and learning flow. Independent chess-editor approval remains part of the private-preview release process. Read the teaching method.