I played two campaigns white winter with whites and in both cases, even though I had conquered much of the 15 target cities required by the scenario I won with the victory point . I have done something wrong or I misunderstood ?

Then it works as to end all war . thanks because mauale spoke only of the city to control

can anyone explain how the sudden death work? I played two campaigns with whites and even though I had conquered and held until the end en more than 15 cities have always won with victory points. thanks in advance and sorry for the bad grammar but are not native English speakers