Be convinced that to be happy means to be free and that to be free means to be brave. Therefore do not take lightly the perils of war.

The line links three ideas in a chain: happiness depends on freedom; freedom depends on courage; and courage is tested most severely in war. Read this way, it is a warning against treating war as a casual instrument of policy or a glamorous proving ground. If a community wants the goods of a free life, it must be prepared for the risks and moral costs that defending freedom entails. At the same time, the final sentence undercuts any romanticism: bravery is necessary, but war’s dangers—material, political, and ethical—are real and should be weighed soberly before conflict is embraced.