How To Saber a Champagne Bottle
Sabrage became popular in France when the army of Napoleon visited many of the aristocratic domains. It was just after the French Revolution and the saber was the weapon of choice of Napoleon’s light cavalry (the Hussars).
As for the physics of sabrage, Wikipedia explains:
The inside pressure of a typical Champagne bottle is around 620 kilopascals (90 psi). The diameter of the opening is 18 millimetres (0.71 in), so there is a force of about 160 newtons (36 lbf) trying to push the cork out of the bottle.
At the opening of the bottle, there is a lip that creates a stress concentration. On the vertical seam of the bottle there is a thin, faintly visible, prepared seam, which creates a second stress concentration. At the intersection of the seam and the lip, both stress concentrations combine and the strength of the glass is reduced by more than fifty percent. The impact of the saber on this weak point creates a crack that rapidly propagates through the glass, fueled by the momentum of the saber and the pressure in the bottle.
Once the crack has severed the top from the bottle, the pressure inside the bottle and the transferred momentum from the saber will send the top flying, typically for a distance of 5–10 metres (16–33 ft).