I think that Berlin is referring to the militia created by Bacon, which consisted of black and white servants. The ultimate goal was to attack natives and both the whites and blacks had joined to attain their own freedom. After Bacon’s death, many feared the rebel militia which united white and black servants that destroyed the colonial capital. They were afraid of the multiracial alliance and wanted to protect their superior status, they gave all the white servants more rights and a higher status while the black servants were permanently enslaved creating a difference. This gave one group freedom and another slavery at the same time. Creating an “out” group got rid of the threat of being overthrown and dispositioned from the superior economical position by a rebel militia containing multiracial affinity.
Many Americans saw the Jay Treaty as an embarrassing surrender to the British. It angered the American people and many Europeans, especially the French.
To colonize is to settle in, and take control of, land outside your own borders. There are many examples through history of powerful countries that colonized various regions of the world in order to gain natural resources or to obtain more land for their citizens to live in.