This is just the kind of question that is of no value or consequence in any way, but you find yourself spending an absurd amount of time thinking about
– Trying in General Questions, because I’m sure other people in chess’ long history have thought about this, and there might be an actual factual answer –
So, obviously this question depends heavily on what circumstances a king could be a regular piece.
So let’s say we start with an ordinary board configuration. Then we have a rule that at the start of the game both players can elect to change one of their pawns to a KingPawn (mmm, king prawn…).
A KingPawn being a piece that moves and attacks like a king, but can be lost without losing the game. But otherwise it’s like a king: it can’t be promoted, or move two squares at the start, or do “en passant”.
What would the value of this piece would be? Would it be more useful than, say, a bishop?
Or can we even go to the level of giving it a score?
(The scores of the other pieces, at game start, being:
Pawn = 1 point
Knight = 3 points
Bishop = 3-3.5 points (some disagreement on bishop value)
Rook = 5 points
Queen = 9+ points (beginners value queens higher))
It would threaten eight squares, the same as knight. A knight is hindered more by the edges, but can move across the board quicker. A bishop threatens between 7 and 13 squares, on average something like 10 squares. A rook threatens 14. So I would say a king pawn would be worth about the same as a knight.
I agree; every chess book that I’ve seen which addresses the question puts the king in the knight/bishop range. Beginners without a lot of endgame experience are sometimes surprised by this, but the king is a fairly powerful attacking piece, once the board becomes empty enough that it can be safely employed.
Indeed, the non-royal King (sometimes called a Mann) is about as powerful as a minor piece, if not more so. He lacks even the Knight’s range but is much handier at close quarters - a King can hold off three connected passed pawns, a Knight is apt to get murdered by them. And of course mate with a King and Mann would be achievable whereas mate by a King and minor piece ordinarily isn’t.
A Knight can fork enemy pieces, a Bishop can pin or skewer, but a King can attack adjacent units, operate on squares of both colour regardless of tempo, and attack both a pawn and the square in front of the pawn - none of which the minor pieces can do.
Taken all in all, in an ending otherwise roughly equal, if you can immobilise the enemy King at a cost of tying up your own Bishop or Knight, you should go for it - your King should be better than the enemy minor piece.
“As an assessment of the king’s capability as an offensive piece in the endgame, it is often considered to be slightly stronger than a bishop or knight – Emanuel Lasker gave it the value of a knight plus a pawn (i.e. four points on the scale of chess piece point value) (Lasker 1934:73). It is better at defending nearby pawns than the knight is, and it is better at attacking them than the bishop is (Ward 1996:13).”
