I am curious how an army moved its pillage? I mean, if every soldier nabbed some pots and some flatware and some jewelry and artwork how did they carry it around with them? Surely a whole city’s worth of loot is cumbersome to tote about and I cannot imagine that squares well with being an army.
(If this is too much of a hijack let me know.)
Accomplices among the baggage train and the camp-followers.
Plus, of course, the soldiers, like any thieves, will be focusing on small, easily-carried, high-value items. The only way pots and pans are going to be looted is if the mess sergeant needs them for the camp kitchen, and in that case, they’ll be hauled by the military’s own mule train or trucks or whatever they have.
No no, no! That’s plunder you’re talking about, not pillage.
And was explained by me above and the folks just below you, that was left to the supply weenies to manage. 
This appears to be the origin of The Purge.
The Wikipedia entry on the Seige of Badajos indicates that it took Wellington three days to restore order to the British soldiers who were sacking the city. However, that wasn’t a three day grant by him; he tried to restore order the day after the city was taken, but it took three days to do so.
The specific time of three days I though was an Ottoman or Islamic tradition, i thought, but can’t find a cite
But the fact that the population of a besieged town faced many days of brutal pillage if they allowed the beseigers to take the town by force (rather than negotiate a surrender) was absolutely universal, regardless of the culture doing the besieging. The Romans even had rules against accepting a negotiated surrender after “a ram had touched the walls”. And even as late as the Napoleonic wars it was a given that a town that forced a siege and lost would face brutal pillaging.
In the case of the mongols a refusal to surrender before a siege resulted in the entire city being wiped out.