Copyright (c) 1887 George S. Parker

The game is played on the following board with this setup:

SOLDIER  - Each soldier has 3 type of moves:

Move to an adjacent cell (orthogonal or diagonal);

Cantering - Jump over a friendly adjacent piece and continue jumping, at its option, as long as friendly pieces remain to be jumped;

A canter move cannot return to some previous visited cell.

Capturing - Jump over an enemy piece, thereby capturing it, in which case it must continue jumping as long as captures are available.

A soldier cannot canter and capture on the same move.

KNIGHT - It has all the soldiers move, plus:
Charging - After a canter move, it may make a capturing move. However, after a Knight starts capturing, it cannot canter anymore on that move.
When cantering a Knight must make a capture if one becomes directly available.
CASTLE - The player's castle are the two cells of his first row.
Once a piece enters the enemy castle, it may never leave. 
A piece in the enemy castle is permitted to move laterally twice during the game. 
You may never enter your own castle except through a capture, in which case the piece must be moved out as soon as possible. If the piece cannot move out through another capture on the same turn, then it must be moved out on the next turn (even if this means declining a capture elsewhere on the board). When moving out of the castle, priority is given to capturing or charge moves.
GOAL - Wins the player that occupies the enemy castle by moving two of his pieces into it. A player also win by capturing all opponent pieces, if he has at least two pieces remaining. A draw is declared if both players are reduced to a single piece. Stalemate is a loss.

Quoting Troyka: Camelot is one of the great boardgames of the nineteenth century, along with Reversi and Halma. Invented in 1887 by George S. Parker, founder of Parker Brothers, it was originally marketed under the name Chivalry. The game achieved a substantial following after its re-release in 1930, with minor rule changes, under the name Camelot. [...] In recent years the World Camelot Federation has rekindled interest in the game. To learn more about the history of Camelot, and to join the Federation, visit Camelot was featured in an article in the seventh edition (summer 2001) of Abstract Games Magazine.

An example

The Black Knight at cell e11 can canter to cell [1] and [2] and then capture through cell [3] and [4]. However, he will loose, because the other player would move his Knight into the enemy Castle.

For more information regarding Camelot, you can also check Mark Thompson's website. There is a ZRF to play Camelot with Zillions made by W. D. Troyka. This game has a patent. You can check it at with patent 1780038. You can read a lot of information from Parker itself, about his claims for Camelot.