conditional moves letting me castle an R that is under attack from an N

that's not legal, is it?

I thought to castle all the squares involved had to not be under attack

Actually, the King cannot be under attack, and cannot move through a square that is attacked, or land on a square that is under attack. That leaves, for white square h1 on the king side that could be under attack, and a1 and b1, that could be under attack on a queen side castle. For black, the squares are a8, b8, and h8.

 Usually, if I do it, I don't even consider if the a1, b1, or h1 is under attack, so I can't really say how common or uncommon it is, but it would be uncommon if not rare to happen before getting solid into the middle game or later in the game. The reason I don't consider it those squares are under attack, is because at that stage of the game, I'm calculating a lot of stuff, and the castle would be part of some bigger strategy where the consideration of those squares being under attack would be irrelevant.

Castling is legal, along as the king and squares between the king and rook are not attacked. Castling is also legal, if only the rook is attacked.

ohhhhhhhhhhhhhhhhhhhhh

hahaha i learnt a new rule xD too funny bro

thanks frank, i have so long to go.......................```````````~~~~~~~~~>~~~~~~~~~``````````~>>>>>>>>>>............................

Almost true, 

Only the squares that the King leaves, crosses or enters need to be free of attack.

For example, the following is perfectly legal:

The Rook's attack on the b1 square does not prevent castling.

wow!!! damn, i wonder how many times i could have castled when I thought I couldn't....

only the squares the K crosses leaves or enters. Hooooooh!

....isn't learning fun ?!

hopefully i can stop discovering more rules of chess soon! are there any other rules of chess that are often misunderstood?

I am quite confident i have a good handle on the 50 move draw rule.

xD got that one covered i think, i mean it applies to all the first moves of pawns, vs other pawns, all the time, eh?

ahhhhhh classic xD and the square next to it, in a queenside castle!

This isn't exactly a rule of the game (how the game works), but a rule of competitions, like time controls for example. 

En passant only for this senario:

White side: the very first move  after black moves a pawn 2 squares on an adjacent file to the 5th rank when your white pawn is on the 5th rank only

Black side: on the very first move after white pawn moves 2 squares on an adjacent file to the 4th rank when your black pawn is on the 4th rank only.

In both cases, the pawn is moved as if the opposing player's pawn only moved 1 square.

The three-fold repetition is actually much more complicated than most players know. (It's in fact so complicated that even many chess engines, and even some chess GUIs, are programmed incorrectly with respect to it. OTOH, the situations where this matters are so utterly rare that chess engines generally don't need to spend precious clock cycles to check those fringe cases. It's less forgivable with chess GUIs, however.)

True, thanks> I guess I meant rules that I might come across on this site, but yeh good to know when they are comp specific.

thanks, yeup.

I once read that this situation happened in a Korchnoi game: his opponent castled when his rook passed across a square which was under attack. Then Korchnoi stopped his clock and made a complaint to the arbiter, who stared him with awe, one of the best players in the world didn't know that move was completely legal!

He knew. He admitted it on his deathbed. He was just biding time.

whoa! such acting under pressure, that's quite the mettle : ) did he end up winning the game?