Before the 19th century, most battles were over within a day
Gettysburg's three days were unusually long for its era; most earlier battles ended in hours because armies could not be fed in the field or fight well at night. Then railways and trenches changed everything. British soldiers who went over the top at the Somme on 1 July 1916 found themselves in a five-month battle.
The English word comes from Old French bataille, recorded in 1297, which goes back through Late Latin to a Germanic verb meaning to beat, the same root that gives us battery. Military thinkers draw lines between scales. A battle is a clearly bounded clash in time, place and forces committed; a limited, indecisive exchange is a skirmish; and when fighting drags on longer than a week, planners often call it an operation. Carl von Clausewitz saw the use of battles to achieve a war's aims as the very essence of strategy. John Keegan offered a neat ideal, the moral then physical collapse of one army, while admitting real battles rarely fit it.
Duration and scale have ballooned. Battles such as Preston in 1648, Leipzig in 1813 and Gettysburg in 1863 were exceptional for lasting three days. Better transport and the trench warfare of the First World War stretched fighting to weeks and months, forcing armies to rotate units so troops did not stay at the front more than about a month. Until artillery and aircraft, the two sides fought within sight of each other; later the word stretched to campaigns like the Battle of Britain and the Battle of the Atlantic. At Midway, five aircraft carriers were sunk without the opposing fleets ever coming into direct contact.
Outcomes turn on numbers, equipment, leadership and ground. At Omdurman, an Anglo-Egyptian force with machine guns and artillery overwhelmed a traditionally armed Mahdist army. Yet clever use of simple weapons can win too: Swiss pikemen turned a defensive weapon into an attacking one, and Zulu armies gained an edge with the iklwa spear. At Alesia, outnumbered Romans prevailed through training. High ground tires an attacker, and dense forest favours the weaker side.
Historians also sort battles by type: pitched battles fought at an agreed time and place, encounter battles where forces blunder into each other, attrition battles like Verdun, and envelopments such as the double envelopment at Cannae. The first reliably documented battle, Megiddo in the 15th century BC, already involved organised armies. The idea of the decisive battle gained popularity through Edward Creasy's 1851 book on fifteen such clashes.
Source: Battle
