Related Rule
United Kingdom of Great Britain and Northern Ireland
Practice Relating to Rule 115. Disposal of the Dead
Section F. Respect for and maintenance of graves
The UK Military Manual (1958) provides: “Graves must be respected and properly maintained.” 
United Kingdom, The Law of War on Land being Part III of the Manual of Military Law, The War Office, HMSO, 1958, § 383.
The UK LOAC Manual (2004) states:
7.36. Graves must be respected and properly maintained. They must be marked so that they may always be found and should, if possible, be grouped according to the nationality of the deceased. Graves registration services must be officially established at the outbreak of hostilities and, as soon as circumstances permit, the adverse parties and any other concerned authorities are required to seek agreement for:
a. The permanent protection and maintenance of grave sites;
b. Access to those grave sites by relatives of the deceased and the representatives of the official graves registration services;
c. The return of remains of the deceased to the home state on that state’s request or, unless that state objects, on the request of the next of kin.
7.36.1. In the absence of agreements relating either to protection and maintenance of grave sites or for the return of the deceased, the authorities of the territory in which the grave sites are situated may (a) offer to facilitate the return of the remains to the home state; and (b) if such an offer is not accepted within five years from the date of the offer, and after due notice, adopt arrangements for dealing with such remains in accordance with their own domestic laws relating to cemeteries and graves. 
United Kingdom, The Manual of the Law of Armed Conflict, Ministry of Defence, 1 July 2004, §§ 7.36–7.36.1.