Quote Originally Posted by Yora View Post
When did we first see battles in which there is major fighting between main forces over multiple days, and what developments in technology and organization made this possible?

It seems to become a frequent occurrence in the American Civil War, but there was also the Battle of Leipzig some 70 years earlier.
Quote Originally Posted by pauly
There have been battles over several days throughout history. In the pre gunpowder era they were more common in Asia than in Europe.

Some factors that make a multiple day battle more likely include.
- Very large armies.
- Both sides having favorable defensive ground.
- A reliance on missile weapons over melee.
- Evenly matched opponents (after taking into account technology differences and terrain advantages).

The two big factors that made 20th century warfare feature multiple day battles as standard
- dispersed formations due to machine guns, smokeless rifles and efficient artillery.
- the ability to command further, through field telegraphs, telephones and wireless. This allows further dispersion of troops and the co-ordination of reserves.
well, its worth noting that the descriptions of several ancient battles imply that it was semi common for the two armies to be in close-ish contact for several days or even weeks before the actual fight, with manouvering for position, shows of strength, minor skirmishes, etc. Often, one side was holding favourable ground, and unwilling to abandon it unless induced to by some external pressure (for example, lifting a siege, or getting home before harvest)

Also, ancient and pre modern armies took a long time to deploy into battle array, often many hours, even with articulated command structures and a clear plan (factors that were often lacking), and the difficulty in doing so would lead commanders to be wary of staying in combat range of an enemy if they had any choice in the matter. So, they'd have their camp some distance back, far enough away to be safe.

Arguably, the biggest reason battles took longer in the 19th and 20th century is switch to firepower as the primary means of combat over shock action. Because of this (relative) reluctance of troops to close into melee, combined the with the (relative) ease of keeping a flintlock in a ready to fire state, it made it practical for an army to sleep overnight only a few miles form the enemy without being suicidally vulnerable to a surprise night attack*, and by extension able to carry on the fight again the next day.

also, its party a matter of what you count as a battle. We split "Waterloo", "Quatre Bras" and "Ligny" into three separate battles, even though the latter two happened at the same time and not too far apart, and involved two wings of the same French army, and the Waterloo happened the next day, and involved the same armies moving directly form one battle to the other. Today, we'd count all three actions as part of the same battle.

It helps that modern combat doesn't really stop at night, so its easier to think of the battle continuing as the fighting doesn't stop.

*not saying that night attacks could not or did not happen, but only that a redcoat could go form sleeping to combat ready in minute or two, by grabbing his musket and cartridge belt and joining the fight in whatever he happened to be sleeping in, while a medieval knight caught asleep needed much longer to strap all his armour on and get ready for a fight.