Best Way to Attack a Castled Opponent.

But I'm really liking all these ideas, so thanks guys.

Does anyone else have other plans to offer?

And is there a difference in which side they castle too (Kingside VS Queenside) ?

Well, I don't see it working unless you have the knight on f3 ready to check with Ng5+ and make way for the queen. I guess it's the definition of the Greek Gift sacrifice...

As for differences in castling side, the queenside is more fragile because the a-pawn ends up undefended, and one tempo has to be used to protect it (either by moving it one step forward or bringing your king do the b-file). Of course, if you already moved your a pawn forward earlier, it's not that big a concern, although the pawn would still be more vulnerable to a sacrifice attack without the king's protection:

Yeah like some other people mentioned, using a pawn storm can destroy the opponents defense. This works well when you castle opposite sides and bring your rooks in :)

If anyone is still interested in this two years later :p

I've found a few things work well:

As clinttherakam said, pawn storm is okay, but a little slow. It's still quite good provided you have, as he said, castled to the opposite side.

A second thing, is that I've started playing on the assumption that they will most likely castle kingside, and therefore Bishop to C4 (as white) sets up a pin early on, that they often castle into. Pins, pins are great :)

Classic Bishop - Queen pin.  Check VERY carefully that nothing can get in the way of your Q, or defend that black pawn, but maneuvering into this particular setup has won me many games.  Obviously, Black can't take the B with the pawn or he would expose the King to check.  It works just as well if the black pawn is on h6, simply capture it with the Bishop.

Try the Harry attack

 What about black pawn to g6, sure he trades a rook for bishop but would black still have a fighting chance?

It really depends on the position. In general, having two bishops vs one or no bishops gives you strong attacking chances, as well as having initiative and space advantage. Don't forget about the "rook lift", many people overlook this idea, but it often allows one to easily breach seemingly impenetrable fortress. In closed positions, pawn march can also be a good idea: if the enemy pawns are at f7, g7, h7 and the king is at g8, for example, the g5-g6 strike, supporter by the h5 pawn, breaks black's castle open. If the opponent has weaknesses in his castle's pawn structure (f7-g6-h7. f7-g7-h6, etc.), then placing a knight on the weakened square, or hitting weakened squares with a bishop and a queen, pose very serious threats to the enemy king.

I purchased the Art of Checkmate a few years ago and am now reading it more often. It is worth the purchase and a super simple book to read. Each game is about a page with that much analysis. But it does have the mating position/concept for each type of mate. 

A general rule is if you have more pieces attacking than your opponent does defending you have a chance for checkmate. I highly recommend looking for the "patterns" of checkmate. This is like knowing tactics and what to look for. It will make mates come more naturally and you will see them from a mile away. Good luck. Attacking for checkmate is a fun adventure.

This is a classic, every chess player should have these patterns memorized. (Not saying you shouldn't have posted it, just saying that it's good stuff!) 

I like the greek gift.. Most players in lower ratings would not think sacrificing a piece for initiative. And that's why it works so fine at my level.

English GM Danny Gormally wrote a book on precisely this subject which might be worth a read. I'll give my two cents on attacking the castled king below.

How you should attack depends on two main factors - whether the pawn structure is open or closed and whether the kings are castled on the same side or opposite sides.

With opposite side castling the best plan often involves throwing your pawns forward to open up their king. For example in many variations of the sicilian white will castle on the queenside and play h4-h5 and g4-g5-g6 to open the g- and h-files and mate (assuming black keeps pawns on f7, g7 and h7). Tal - Koblents is a prime example of this (http://www.chessgames.com/perl/chessgame?gid=1139363)

If the kings are castled on the same side then this plan becomes a lot more risky as you endanger your own king by moving its pawn protection forward. Generally it will only work if the pawn structure in the centre is close and you have more space on the wing with the kings - for example white's attack in the f4-tarrasch variation of the french, or black's classic King's Indian pawn storm. Piket - Kasparov came to mind as the most famous example of the latter. (http://www.chessgames.com/perl/chessgame?gid=1070485)

If the centre is more fluid your opponent has more potential to punish you for weakening your king, which is why attacking plans are more often piece based. Positions where the attacker has an IQP (isolated queens pawn) often feature a piece attack, for example Stein - Petersons (http://www.chessgames.com/perl/chessgame?gid=1132315). I am a far weaker player than those I have mentioned, but I built up a very powerful attack in this fashion (including a rook lift to the kingside) against English GM Glenn Flear, before missing a crushing blow in time trouble and having to settle for a draw. (https://chess-db.com/public/game.jsp?id=436550.400165.150587648.29423)

Some patterns you should recognise when attacking include:

The Greek Gift Sacrifice (Bxh7+, Ng5+, Qh5 with unstoppable mate). The warning signs for this include a strong attacking pawn on e5 and a bishop on the b1-h7 diagonal, while black doesn't have many defences on the kingside. 

The double bishop sacrifice (Bxh7+, Qh5+, Bxg7, Qg5+, Rd3-h3#) is similar, with powerful twin bishops on the a1-h8 and b1-h7 diagonals necessary for its success.

The classic anti-fianchetto yugoslav-style attack (Bh6, h4-h5-xg6, Bxg7, Qh6+, Qh7#, maybe with a Nd5 thrown in somewhere) common in dragon and modern positions.

The grand-prix anti-fianchetto attack (Qe1-h4, f4-f5, Bh6, Ng5, fxg6, Bxg7, Rxf6, Qxh7#) common in the grand-prix attack in the sicilian and the austrian attack in the pirc.

Of course the defender will try to stop you carrying out the above, but they are often what you aim for.

If you got this far I hope this was helpful and thanks for reading! Let me know if you have anything to add.

thanks @dghg1810 that was really interesting

Happy to help

One of the best 50 pages of chess literature ever written is the 2nd chapter of the old GM's Keres and Kotov book, The Art of the Middle Game, "Strategy and Tactics of Attack on the King."

It goes into detail of how to determine if you should castle on opposite sides - where a Pawn Storm is called for, and how you should attack with Pieces when castling on the same side.

When I coached a very successful high school chess team, that chapter was mandatory reading for my players - along with Nimzowitsch's chapter on Overprotection from My System and Jeremy Silman's (then the reasonably sized 1st Ed.) of How to Reassess Your Chess.

Here's a game where I suspected my opponent would castle K-side after I castled Q-side and saw I had a Pawn Storm advantage if he did: I used Keres and Kotov's rules for determining if I could get a Pawn Storm in first (that's who wins!) if I castled opposite my opponent which basically is answered by 3 questions: 1) Are my attacking P's closer to the opponent's K than his are to mine? 2) Do I have fewer of my Pieces blocking my own P's from attacking than he does with his?, 3) Does he have more Pieces that have to jump out of the way of my storming P's, costing him tempos?

Note that after Black castled on move 9, I (White) exchanged off his fianchettoed KB and then my next four moves were all Pawn moves storming his King. I didn't know if they were great moves but I knew, thanks to Keres and Kotov, that if my Pawns advanced to his castled position before his got to mine, I had a good chance to win.

Note also how, on moves 13 and 15, Black had to move N's out of the way of my storming P's, costing him tempos and giving me the edge I needed in what was a smartly defended game by By Black:

Nice game, thank you for the pawn storm tips. Another tip that goes with this is if you can get your pawn to attack the base pawn of a chain you can dismantle it, open up the board and become an attacking machine.