See answer below

pacification: The two nations agreed to settle their differences with pacification instead of violence.
propaganda: The younger generation took to the internet for information as mainstream media was egregiously rife with propaganda.
appeasement: The prime minister was voted out of office in the next elections as his appeasement tactics cost him the favor of the people.
tyranny: The populace suffered under the cruel ruler’s tyranny.
disarmament: It was a global shock when the sanguinary dictator decided to sign disarmament treaty.
treachery: The general knew that his act of treachery would cost him his life, should his plans go awry.

See sample answer below.

Original sentences:
pacification: The two nations agreed to settle their differences with pacification instead of violence.
propaganda: The younger generation took to the internet for information as mainstream media was egregiously rife with propaganda.
appeasement: The prime minister was voted out of office in the next elections as his appeasement tactics cost him the favor of the people.
tyranny: The populace suffered under the cruel ruler’s tyranny.
disarmament: It was a global shock when the sanguinary dictator decided to sign disarmament treaty.
treachery: The general knew that his act of treachery would cost him his life, should his plans go awry.

Sentences rewritten with antonyms:
• The two nations agreed to settle their differences with violence instead of pacification.
o The sentence is a little humorous, because it suggests the nations were able to interact enough to have a meeting, but they only agreed on still wanting to fight.
• The younger generation had no need to take to the internet for information as mainstream media was rife with truth.
o This sentence is humorous in its optimism. It is common knowledge that most mainstream media anywhere will be filled with bias, so it is funny to think of a world in which it only shows objective truth.
• The prime minister was voted out of office in the next elections as his provocation tactics cost him the favor of the people.
o This sentence’s meaning doesn’t change. Whether the prime minister’s appeasement or provocation tactics cost him the favor of the people, the outcome is the same, and it is safe to assume both were similarly inappropriate.
• The populace was lucky to live in a democracy.
o This sentence is positive, while the original was negative.
• It was no shock when the sanguinary dictator decided to sign a militarization treaty.
o This sentence is very unsurprising, while the original was surprising.
• The general knew that his act of loyalty would cost him his life, should things go according to plan.
o The original implies the general will die if his betrayal comes to light, and frames him negatively. This sentence frames the general positively, because it implies he will die in order to stay loyal.