When did Classical chess end and Modern begin?

Did it begin with Morphy or Steinitz, or neither?

Also was Morphy the most dominant chess player of all time?

Steinitz.

by the time alekhine arrived on the scene modern chess was already firmly established. but alekhine was perhaps the first guy who showed the real possibilities in the game.

I thought the modern ara began when Steinitz introdused positional play in 1873?

There are 3 schools of thought.  It really has nothing to do with the specific date of the game.  It has more to do with the time of its popularity.  Magnus Carlsen plays "Classical Chess" even though he plays in the 21st century.

The 3 schools of thought are:

Classical - You fight for control of the center via pawn occupancy.  For example, 1.e4 e5 or 1.d4 d5 are considered "Classical Openings".

Modern - You fight for control of the center via piece occupancy.  This is the LEAST COMMON of the 3 schools of thought.  Probably the best example would certain lines of the Sicilian where piece play controls everything, like the Four Knights Sicilian or the Sicilian Pin Variation.

Hyper-Modern - You relinquish the center to your opponent on the basis that he or she will overextend, and then you proceed to chip away at it.  Typically this means little to no advancement of the center pawns (and definitely not 2 squares), leaving the center for your opponent to grab, figuring he or she will overextend.  Prime examples of this are just about any flank opening (e.g. English, King's Indian Attack, Reti, etc) along with defenses that allow White to freely grab the center, like the King's Indian, Grunfeld, Alekhine, etc.  Typically, to be deemed a "Hypermodern Opening", it must follow a few principles, like No early advancement of the central pawns more than 1 square, at least 1 Bishop must be Fianchettoed, etc.

Most openings can be classified in one specific category.  Then there's this opening called the Nimzo-Indian Defense.  Some will argue it's a Classical Opening as it prevents e4 by White, and many lines often see Black playing c5 and d5.  Some will argue it's a Modern Opening because c5 and d5 break open the center and the middle of the board is cluttered by pieces.  A third group will argue it's a Hypermodern Defense in that Black doesn't play an early d5 or e5, and fienchettos his LSB to b7.  In reality, the Nimzo-Indian doesn't have a fixed pawn structure like say, the French does.  The Nimzo has the most diverse of pawn structures of all the main stream openings, and I don't think you can classify it as one opening type over another.  The 4.e3 b6 lines would tend to be more hypermodern in nature while the 4.e3 O-O lines tend to be more classical in nature.

During the second round of the tournament in Mährisch-Ostrau 1923.

I was under the impression that modern chess began with Steinitz, Hyper modern chess began with people like Nimzowitsch. Now I did not mean that this was linear in any way, and that when one began that the other ended.

ah, yes. I believe it was the game Reti vs Hromadka (English, 26 moves, 1-0).

The Romantic School died, and the Classical began with Stienitz and Tarrasch. About 1880.

The Classical School was not usurped, but rattled, by the Hypermodern School in 1920's. Led by Nimzovitch and Reti.

The next Chess Revolution took place (more quietly) with the Soviet School. By Botvinik, Keres, Bronstein, and others.

But which style was the right one? The answer was simple: None! The first truely modern players were (among others) Spassky and Fischer. They who realized style was, by definintion, the same a weakness. It implies that you are bad at some aspect of the game.

Instead, they embraced everything useful from all schools which had come before, and threw out whatever they found useless. "Rounded" was their watchword.

Thank you very much varelse1, that was the most helpful response yet. :-)

John Watson in his book Secrets of Modern Chess Strategy marks the divide at the death of Nimzowitsch in 1935.  He admits this is an arbitrary divide and that no such divide really exists since chess careers of pioneers span decades, but it's one respected author's opinion.

Classical chess did not end. It is played still today. You can maximum say that when "hypermodern" (It is not hypermodern, it was just against classical, but it is accepted already) began.

what is not hypermodern?

i agree

Well, if you can think up a catchy name for this New Era, and publish a book about it, history will remember FirebrandX as the "Chronicler of the 21st Century's Chessplayers."

That was the day I invinted Modern Chess!! November 5th, 1955!!!