Who and how did people clean up a city or battlefield during WWII?

Hi, great question! I can't really speak for the Eastern Front, the Pacific, and Italy, but I can give you an interesting example from The Netherlands. I'm employed in ordnance removal and in the preparatory phase of most project I come across a lot of archival material from the 1940s and 1950s concerning this issue.

My example is related to the cessation of hostilities in the province of Zeeland, The Netherlands, of which the southern part (Zeelandic Flanders) was liberated by 1 november 1944. The area had suffered greatly at the hands of both the German occupier as well as the Canadian, British, and Polish liberators in terms of physical damage during Operation Switchback, Operation Vitality, and Operation Infatuate during September and October of 1944. The Germans had dug in deep along the Atlantikwall that lined the coast, and in 1943 had also built extensive landward fortifications (following the Japanese experience with seizing Singapore two years earlier). The 2nd Tactical Air Force had bombed virtually everything to pulp between Seine and Scheldt after the breakout from Normandy in August, and Zeelandic Flanders was no different. German fortifications remained largely unscathed, and the Canadians had a hard time of it clearing the area. The Conscription Crisis contributed to Canadian use of heavy artillery in the area, and by the end of the fighting about 80% of buildings in the area had been levelled. Use of tactical and strategic inundations furthermore complicated the situation in the low laying areas of the region.

In the winter and spring of 1944/45 the Dutch government-in-exile started setting up a military administration in the region with the help of British military authorities. Primary objectives of this Dutch miltiary administration were the clearing of explosives, the securing of important installations, the returning of refugees to their livelihoods, and the starting of food production efforts as soon as the situation allowed.

Between February and May 1945 most clearing efforts of rubble and ordnance were undertaken by British-trained rear-echelon Dutch troops; military labour at its best and finest. It became clear quickly that this was risky, and caused unnecessary casualties that brought morale down, so as soon as German POW's were acquired from frontline British and Canadian troops, these tended to be press-ganged into doing this work. Especially the clearing of minefields and Atlantikwall emplacements was conducted by German POW's. By late 1945 it became less desirable to do so as the UN considered it a military offense, in disregard of the Geneva Convention, leading to an immediate labour shortage in the region.

As the military authority was replaced by civilian authority from 1945 to late 1946, civilian contractors were increasingly paid and employed to engage in rubble clearing activities where they had not been done by troops. In the case of a town called Breskens it was not until 1953 that all rubble from the devastating months in 1944 had been cleared. The final bunkers of the Atlantikwall that did not become heritage sites were removed in the late '60s and early '70s.

Now that was the story from the governmental level. In practical terms, survivors of the artillery- and aerial bombardments of the region would approach the rubble- and ordnance clearing very diversely. In the case of Breskens it is notable that especially people from outlying areas (mostly agricultural workers, smallholders) were often quick to volunteer any remaining equipment or pack animals to assist the townspeople. In return they would secure luxury goods and/or made sure that the towns people did not come to their farmsteads to claim their resources/scarce foodstuffs in the immediate period of shortage/scarcity.

Townspeople that had not fled Breskens after the bombardment and had survived the ensuing ground fighting bargained, bartered, cajoled rear-echelon troops in the area into assisting their efforts, and often made do with what scarce equipment they had. The townsfolk relied heavily on pre-war systems of charity organised by the Protestant and Catholic Churches, and used these networks to obtain subsistence while their area of habitation was still in ruins. A nice example of networking in this case is the public employment - by utilitarian public demand - of the strangely intact firefighting force of a biscuit factory on the outskirts of town.

With 80% region in ruins, many people had lost their homes, making housing the pre-eminent issue in the initial months of 1945. The people of Breskens cleaned out some 70 of the about 280-300 bunkers and strongpoints in the area to live in. These were considered more comfortable than allied relief tents, Nissen huts, and the makeshift housing provided by the Dutch government. The last of the 'bunker houses' was vacated in 1951, some six years after VE-Day. It must finally be remarked that the fortifications were remarkably comfortable in terms of running water, electricity and heating, and that allied bombardment had barely succeeded in disrupting the closed utilities system of the fortifications, while destroying a significant amount of munitions storages.

I hope this gives you a very local picture of what the immediate post-combat civilian situation in WWII might look like. If you have any further questions, don't hesitate to ask!

As for sources:

L.W. De Bree, Zeeland 1940-1945 Deel I

G.J. van der Ham, Zeeland 1940-1945 Deel II

Ben Muller, Breskens onder Beton

Bollen, De Canadezen in Actie

I have also referenced archival material of the Provincial Archive of Zeeland, and the municipal archive of Oostburg (of which Breskens is nowadays part); please let me know if you want me to provide the precise materials for your perusal.

EDIT: Source formatting