Offense Defense Aggression and Mastery

A good chess offense must look at strategy and tactics at the same time - short term moves which focus on developing temporal, positional, and immediate material advantages are called tactics; strategy focuses on larger goals and mainly converting temporal and positional advantages into advanced material advantage.  The final longterm goal or strategy in mind is checkmate.  So the fact that material advantage must be present is a given but not absolutely neccessary for check mate.

A good chess defense is either a superior inititive in offense or a series of defensive moves to protect ones king from attack.

With this being said one could argue the points that chess is a game of aggression mainly offensive in nature and that victory goes to the player with superior inititive and thought.

Pawn chains castling and en passant are a few parts of the game of chess. These things can all be mastered individually by studying the games various parts.  However a full mastery of the game comes with a full practice of all aspects of the game.  Therefore playing the game as a whole and not just studying its various parts can never be underrated.  Have a nice day.