In 1792 France unleashed a new form of warfare in Europe. Faced with the well-drilled Austrian and Prussian armies, the French introduced the tactic of mass skirmishing by tirailleurs. Soldiers were thrown forwards and told to fight in open order. Moving quickly and making use of cover, they fired on the enemy line, annoying it, goading it, and all the time distracting it from the infantry columns coming up behind, bristling with bayonets, ready for the charge and a shock action. Of these tirailleurs, the best were the professional chasseur light infantry battalions, raised and trained in the army of Louis XVI; but they were too few in number. A patriotic appeal for light infantry volunteers was made, and within two years the original twelve battalions became ninety strong. By the time of Napoleon's invasion of Russia in 1812, there were 185 battalions of light infantry in service, with hundreds of voltigeur light companies attached to the regular line infantry battalions.