A mass grave is a grave containing multiple human corpses, which may or may not be identified prior to burial. The United Nations has defined a criminal mass grave as a burial site containing three or more victims of execution, although an exact definition is not unanimously agreed upon. Mass graves are usually created after many people die or are killed, and there is a desire to bury the corpses quickly for sanitation concerns. Although mass graves can be used during major conflicts such as war and crime, in modern times they may be used after a famine, epidemic, or natural disaster. In disasters, mass graves are used for infection and disease control. In such cases, there is often a breakdown of the social infrastructure that would enable proper identification and disposal of individual bodies. History Mass or communal burial was a common practice before the development of a dependable crematory chamber by Ludovico Brunetti in 1873. In ancient Rome waste and dead bodies of the poor were dumped into mass graves called puticuli. In Paris, the practice of mass burial, and in particular, the condition of the Cimetière des Innocents, led Louis XVI to eliminate Parisian cemeteries. The remains were removed and placed in the Paris underground forming the early Catacombs. Le Cimetière des Innocents alone had 6,000,000 dead to remove. Burial commenced outside the city limits in what is now Père Lachaise Cemetery. War Mongol Invasion of Kievan Rus' A mass grave containing at least 300 bodies of victims of a Mongol invasion of Kievan Rus' in the year 1238, was discovered during an excavation in 2005, in Yaroslavl, Russia. Thirty Years' War The Thirty Years' War, in the 17th century, was Europe's deadliest religious conflict. In the Battle of Lützen, 47 soldiers who perished were buried in a mass grave. Archaeological and osteological analyses found that the soldiers ranged in age from 15–50 years. Most corpses had evidence of blunt force trauma to the head while seven men had stabbing injuries. Most of the soldiers died from gunshot wounds inflicted by pistols and cavalry carbines. Napoleonic Wars Several mass graves have been discovered that were the result of Napoleonic battles, mass graves were dug for expeditious disposal of deceased soldiers and horses. Often soldiers would plunder the substantial quantity of corpses prior to burial. Generally the mass graves were dug by soldiers or members of logistical corps.