Overloaded pieces

You checked. The bishop was defended, the back rank was covered, every count came out right, and you still finished the game a piece down.

The counting was not wrong. The problem is that one of your pieces was answering two counts at once, and it only gets to answer one.

Say it in the blunt form and it stops being subtle: a piece guarding two things is not really guarding either one. It is guarding whichever one your opponent decides to leave alone.

One guard, two pieces

The knight on d7 is doing honest work. It defends the bishop on e5, which White's bishop attacks, and it defends the bishop on b6, which White's rook attacks. Each black bishop is attacked once and defended once. Look at either one on its own and it is safe.

Look at them together and the knight is a piece short.

1.Bxe5 and Black gets to pick which count to honour. 1...Nxe5 honours the first and abandons the second: 2.Rxb6, and the bishop goes, because the knight that was guarding b6 is now standing on e5. Decline the recapture instead and White is simply a bishop up, having taken one for free.

There is no third reply. That is the signature of an overload: not “the defence is awkward”, but “there are two demands and one piece”.

One guard, a piece and a square

The second job does not have to be a piece. It is often a square, and squares are where this turns fatal, because a square never looks like work.

Black's rook has been given two jobs it never agreed to. It defends the bishop on d5, and it holds e8, which is the only reason there is no mate on the board already.

1.Rxd5 and the two collide. 1...Rxd5 2.Re8# arrives on the square the rook stopped watching the instant it stepped off the eighth rank. So Black does not recapture, moves the rook somewhere useful instead, and plays the rest of the game a bishop down.

Notice what White never needed: no sacrifice, no long line, no combination. White took a defended piece, because the defender was not free to answer.

This is the real cost of a weak back rank, and it is not the mate. Every piece you own that also has to cover the first rank is working two jobs in every position, all game, and it takes exactly one capture somewhere else to turn that into a bill.

The same thing, pointed at you

Now it is your rook, and it is doing both jobs at once. It defends the bishop on d4, and it is the only thing between your king and the back rank.

If it were Black's move, 1...Rxd4 would win a piece and you could not answer it: 2.Rxd4 Re1# means you never get to take back, so the bishop just goes.

It is your move. So spend it. 1.h3, or 1.Kf1, and the rook stops being the last line of defence. The bishop is genuinely defended now, because the piece defending it has nothing else to do.

Neither move develops anything. Neither one looks like progress. Either one is worth a bishop, and that is the practical version of this whole article: most of the time you will not be the player finding the overload, you will be the player who has one, and the move that fixes it is small, ugly and free.

The tell

Overloads are findable, but not by looking at what is attacked. Look at your defenders and count backwards.

1. Pick a piece that is doing defensive work. Anything that is the reason another piece or another square is currently safe.
2. Ask what else it is doing. A second piece, a square near your king, a pawn, a file. If the answer is more than one thing, it is overloaded now, not later.
3. Ask what happens if it is made to choose. You only need one capture or one check that asks for both jobs in the same move.

The job people miss is the back rank, every time, because it never feels like a job. It is silent right up until it is mate.

The habit

This is removing the defender with the hard part already done for you. There, you had to take the guard or chase it off its square. Here the guard is already stretched across two duties, and all you have to do is ask for both.

So the counting habit grows a third layer. Count the attackers and the defenders. Then count the defenders' own attackers. Then ask what each defender is doing besides the thing you are counting. That last question is where most of the free material between 1000 and 1800 actually sits, in both directions, and almost nobody asks it.

Then go and see what it has cost you. Filter your games by hanging a piece and losing the exchange, find the ones where the piece you lost was defended at the time, and look at what the defender was doing. A good share of them are not blunders in the usual sense. They are pieces that were asked for one thing too many.