Popularized during the reign of Napoleon, Sabrage is the fine art of opening champagne bottles with a champagne sword. It's a technique that requires a sound understanding of the physics involved.
The carbon dioxide released during the second fermentation creates a significant amount of pressure (620 kilopascals) in champagne bottles. The bottle opening is only about 18 millimeters and hence, the cork experiences a force of about 160N which tries to push it out of the bottle.
At the lip of the bottle and the vertical seam running down the body, a stress concentration is created. At the point where these two stress concentrations intersect the glass is weakened by 50% of its strength, which increases its tendency to explode at any moment. When this weak point is hit by a blunt saber, the impact forms a crack which extends across the neck of the bottle due to the pressure in the bottle. The transferred momentum from the saber and the pressure inside the bottle sends the top flying for about 5-10 metres. Fascinating, isn't it?