Sabrage is an elaborate technique of opening a Champagne bottle with a sabre, traditionally used at ceremonial occasions. The sabre is slid along the body of the bottle to break the entire lip clean-off away from the bottle, leaving only the base and neck of the bottle open and ready to pour. The force of the blunt, back-side of the sabre hitting the lip breaks the glass to separate the collar from the neck of the bottle. The cork and glass collar remain together after breaking away from the neck.
There are several stories behind the start of Sabrage Champagne. One talks of officers in Napoleon’s army or light cavalry (the Hussars) returning home after a victory. Cheering villages would hand bottles of Champagne as tokens of appreciation for their gallantry.

 

As the soldiers were mounted on horseback it was difficult to hold the reins and remove the foil, wire cage (muselet) and the cork, so the soldiers simply took out their sabres and struck it against the lip of the bottle with an upward blow and sabre off the cork and drank from the bottle. Napoleon was known to have said; "Champagne - in victory one deserves it, in defeat one needs it”. This quote may have encouraged this celebrational extravagance.
The actual science behind this action is the meeting of the glass lip at the top of the bottle just below the cork with a firm hit of a sabre's back-edge and at the weakest point of the glass seam in the bottle. When performed on a suitably chilled bottle of Champagne, the cork and glass lip fly away, spilling little of the precious Champagne. The pressure inside a bottle of Champagne ensures that no glass falls back into the bottle making it safe to enjoy.
There is a tool as a Champagne sword (sabre) is an instrument specially designed for Sabrage. Some swords have short blades, around 30 centimetres long and resemble large kitchen knives, although others have much longer blades. The side of the blade used should always be blunt - a sharpened edge is dangerous because in sabrage it is the impact point that is key. With practice and confidence a Champagne bottle can be opened with a spatula using the same method - or even a large spoon.
The bottle neck is held at an angle of approximately 45 degrees and the sword resting on the seam of the bottle. The experienced sommelier can open the bottle with little loss of Champagne. However, it is advised to allow a small flow in order to wash away any loose shards of glass that may be sticking to the neck. The first glass poured should also be checked for small glass shards - though not always easy with the mouse and bubbles.
A Champagne bottle has a considerable amount of internal pressure. With the glass made to a thickness that can contain the pressure caused by the release of carbon dioxide during the secondary fermentation. The inside pressure of a typical Champagne bottle is around 90psi. The diameter of a normal bottle opening is 18 millimetres, so there is a force of about 160 newtons (16.3 kgf) trying to push the cork out of the bottle.
At the opening of the bottle, there is a lip that creates a concentration of stress. On the vertical seam of the bottle there is a thin, faintly visible seam, which creates a second stress point. At the intersection of the seam and the lip, both stress points combine and the strength of the glass is reduced by more than 50%. The impact of the sabre on this weak point creates a crack that rapidly propagates around the glass neck, fuelled by the momentum of the sabre and the pressure inside the bottle. Once the crack has removed the top off the bottle, the CO2 pressure and the transferred momentum of the sabre will send the glass lip and cork flying, typically 5-10 metres.
Some consider the sabre a theatrical alternative for the sometimes clumsy twisting and explosion of the cork, hitting the wall or ceiling when opening the bottle and, more especially, a very spectacular way of celebrating Champagne!