Humanity's Strongest Weapon is the fiftieth chapter of Dr. Stone manga.
It shows Tsukasa Empire Fortress with bridges, campfires and tree houses.
Another girl tells about how they have to work everyday that they were practically slaves. Tsukasa asks Hyouga about rich fat old men.
They plan a preemptive attack as Gen tells that Tsukasa Empire has more soldiers the more time passes by. Senku plants to use the most powerful weapon in 2 million years of humanity and its not Nuclear Weapons but Communication Technology. page 11-15