The year is 204 B.C., and Publius Cornelius Scipio stands, blade and standard in hand, over now-conquered Utica. The numerically superior forces of Hasdrubal and Syphax almost completely annihilated in a nighttime assault by the Romans, and the Carthaginian field forces were entirely out of commission in Northern Africa.
The Carthaginian Empire is the verge of ruin, with Scipio's forces clear to take the capital -

And lo! Envoys appear.
Not just any envoys, but 30 Members of Carthage's Council of Elders, the highest and most respected spokesmen for the state.
They prostrate themselves before Scipio, and beg his forgiveness. They blame the entire war on the ambition of Hannibal, and forsake him. They desire peace...
...and Scipio says yes, giving them entirely reasonable terms considering the gravity of the situation.
Then, as with everything in life, times change. Scipio's supplies from Rome are blown off course, and the transport ships run aground near Carthage.
The Carthaginian war-faction now overrides the peace faction, and they seize the supplies. Simultaneous with Hannibal's massive force of 24,000 men being recalled from the Italian Peninsula, the tables have turned - and the war is back on.
It's worth noting that there's always multiple factions in any side. There might even be multiple opinions - factions, in a way - inside a single person.
Negotiators will always claim to speak for the whole of their camp when it suits them. And yet...
Bear this in mind. Even when one faction of an opposition is friendly to you, or wants peace, there is almost always a war faction. Delays in calendar time let events change and initiative shift. You cannot rely too closely on one person speaking passionately to you if they don't have the undivided and unopposed respect of everyone significant in their camp... and consistency in their opinions, and integrity in abiding their decisions.