With trade, a war abroad will have fallout at home. But while trade has the deterrent effects of powerful weapons, is far preferable because of its other advantages. Where weapons are expensive, free trade brings prosperity and freedom. Where weapons bring terror, free trade fosters harmony and encourages people to resolve disputes without violence. Richard Cobden, a nineteenth century British industrialist and politician, often argued in favor of trade over armaments to discourage war.
Free trade is indeed the wellspring of peace.
It is the natural, voluntary interaction of people for mutual benefit. Trade does not require force. It is protection that requires force, for it consists in preventing people from doing what they want to do. In order to set up an argument linking free trade to peace, it is useful to first look at the incentives inherent to a world where borders are shut by governments. In such a world the incentive is for war.