Short answers, pulled from the story.
Napoleon Bonaparte replaced rigid line formations with flexible column attacks that prioritized speed and maneuverability over static defense. These changes emerged from the chaos of the French Revolutionary Wars before he took command.
A soldier standing in a square formation faced four sides of enemy fire using four to six ranks deep to protect against cavalry charges. Each side held one or two rows of men with fixed bayonets pointing outward to prevent horses from charging directly into the infantry's rear or flanks.
Commanders recognized mobile artillery as essential for shifting battle tides by 1750 after King Gustavus Adolphus first massed light artillery into batteries during the Thirty Years War. A battery contained between six to eight guns plus one or two howitzers requiring six officers and 100 to 150 men to operate effectively.
Smoothbore muskets could not match the range or accuracy of rifled barrels which emerged in the mid 19th century to render old tactics obsolete. The flintlock musket had an effective range of only 50 to 80 yards against man-sized targets while black powder smoke often obscured visibility on crowded fields.
Napoleon declared that moral force rather than numbers decided victory because soldiers faced coercion from officers wielding swords or halberds if they fled. Officers used judgment to determine the exact moment for bayonet charges where fear of bayonets inspired by shining metal often caused enemy units to rout before contact.