Undermining Tactics: Remove the Guard, Overload and Deflection
My First Book of Chess Tactics by David MacEnulty we read:
Undermining Tactics: Remove the Guard, Overload and Deflection
These are all ways of diverting a piece from its task. Each of these has a slightly different meaning, but they all have to do with making an enemy piece leave a protective post, or possibly taking advantage of the fact that it cannot leave a protective post. If you can make the protecting piece leave, whether by taking it (removing the guard), forcing it to take one of your pieces (overload), or chasing it away (deflecting), you can then get the piece it was guarding.
Remove the Guard
Removing the guard simply means taking a piece that is guarding something else that you can also take. If you first knock off the guard, then there is nothing protecting the treasure. Take the guard, then take the treasure.
Overload
An overload is also called an Overworked Piece, which means one piece that is doing two jobs. If you make it do one of the jobs, it will be out of place for the other
Deflection
In a deflection you chase a piece away from an important defensive post. You can do this by either attacking it to make it move away, or by forcing it to take one of your pieces. In accepting your sacrifice, a piece will have been deflected away from its original position, and you can then take advantage of its absence. Some writers call this idea Distraction or Driving Away.
Chapter 3, Tactics Overview, p.16
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