True, ceasefires can be used for many goals, but the goal of the third party who instigates a ceasefire is usually to bring the warring factions to a negotiating table. At least "officially".

Bring to table and then kill them. Youngest example I know: mass killing of Ukrainian soldiers in Illovaysk by Russian army after promising of fire cease. They break lot of laws, rules and memorandums before that, so one more/one less does not matter.

Wars begins where diplomacy ends. To return to diplomacy, defending party must demonstrate power first, to be considered as equal, to talk with. Few thousands of dead Russian soldiers forced Russia to Minks and diplomacy.