The Cuban Missile Crisis ended with a deal nobody could know.
From 16 to 28 October 1962, the USA and Soviet Union stood on the brink of nuclear war over missiles in Cuba. Publicly, Khrushchev withdrew them in exchange for a no-invasion pledge. Secretly, the USA agreed to remove its Jupiter missiles from Turkey within months. Kennedy looked like the winner because that concession stayed hidden for decades.
Useful: Who appears to win a conflict often depends on which part of the deal is public.
Source: en.wikipedia.org