The Wealth of Nations by Part 4 Chapter 7 Page 113

secondly, in the revenue which they furnish for the support of its civil government. The Roman colones furnished occasionally both the one and the other. The Greek colonies, sometimes, furnished a military force, but seldom any revenue. They seldom acknowledged themselves subject to the dominion of the mother city.

They were generally her allies in war, but very seldom her subjects in peace.

The European colonies of America have never yet furnished any military force for the defence of the mother country. Their military force has never yet been sufficient for their own defence; and in the different wars in which the mother countries have been engaged, the defence of their colonies has generally occasioned a very considerable distraction of the military force of those countries.