Final answer:
Okonkwo knows the people will not go to war after he kills a colonial messenger and they react with dismay, indicating their unwillingness to join him in violent resistance against the colonizers.
Step-by-step explanation:
Okonkwo realizes that the people will not go to war after he kills a colonial messenger and looks around to see his people's reaction. Instead of joining him or showing readiness to fight, they are shocked and dismayed by his action. This pivotal moment, filled with despair, indicates to Okonkwo that his hopes for war to reclaim their traditional way of life are dashed, as the people of Umuofia do not share his willingness to resort to violence against the colonizers. His understanding of the situation is fully realized when he sees that he stands alone in his violent resistance, which is a demonstration of how colonialism has successfully begun to erode the unity and warrior spirit of his people.