Related Rule
United Kingdom of Great Britain and Northern Ireland
Practice Relating to Rule 112. Search for and Collection of the Dead
The UK Military Manual (1958) provides: “Belligerents must at all times, and particularly after an engagement, take all possible measures to search for the dead”. 
United Kingdom, The Law of War on Land being Part III of the Manual of Military Law, The War Office, HMSO, 1958, § 381.
The UK LOAC Pamphlet (1981) provides: “Combatants are required … to search for the dead.” 
United Kingdom, The Law of Armed Conflict, D/DAT/13/35/66, Army Code 71130 (Revised 1981), Ministry of Defence, prepared under the Direction of The Chief of the General Staff, 1981, Section 6, p. 22, § 3.
The UK LOAC Manual (2004) states:
Additional Protocol I encourages the parties to try to make arrangements for joint teams from both sides to search for, identify and recover the dead from battlefield areas, such teams to be respected and protected while carrying out those duties. 
United Kingdom, The Manual of the Law of Armed Conflict, Ministry of Defence, 1 July 2004, § 7.38.1.
In its chapter on maritime warfare, the manual provides that “parties to a conflict are also under an obligation, particularly after an engagement, to take all possible measures, consistent with their own security … to search for the dead”. 
United Kingdom, The Manual of the Law of Armed Conflict, Ministry of Defence, 1 July 2004, § 13.129.
With regard to internal armed conflicts in which the 1977 Additional Protocol II is applicable, the manual further states:
“Whenever circumstances permit, and particularly after an engagement, all possible measures shall be taken without delay … to search for the dead …”. 
United Kingdom, The Manual of the Law of Armed Conflict, Ministry of Defence, 1 July 2004, § 15.44.