By 1750, the Virginia colony was enjoying prosperity. Numerous large plantations had come into existence. As more and more soil became impoverished due to a lack of crop rotation, non-use of fertilizer and the intensive planting of the tobacco crop which requires a rich soil, additional land was purchased and added to the existing homestead. Consequently, plantations of 100,000 to 300,000 acres became common, especially around the Tidewater area. The larger the tobacco plantation, the greater the need for cheap labor became apparent. Consequently, the number of Negro slaves increased in Virginia until by 1750, there were approximately 115,000 Negroes and approximately 170,000 free whites. The increase in huge plantations caused the middle class tobacco farmer to migrate westward as he could not successfully compete with the larger tobacco planters. The Virginia plantation owners had become accustomed at this time to allowing the London tobacco merchants to act as their bankers: they would order their necessities, supplies and luxuries (glass, silver, china) via their tobacco credits. Such a system furnished an immediate advantage for the plantation owners but also created a situation whereby the Virginia planters became heavily indebted financially to the London merchants. The plantation owners also became the influential individuals within the colony--politically, economically and socially. Thus, Virginia at this time was practically ruled by an aristocracy. Although the governing power of the assembly had increased gradually, the political power of the commoner or average citizen had not increased accordingly. Membership in the Virginia Council was considered a position of the greatest prestige and was almost an hereditary position. The two required qualifications were wealth and social position. The era of aristocratic living which predominated in the Virginia Colony between 1700-1750 is often referred to as the "Golden Age" of Virginia's colonial history. _The Pre-Revolutionary War Era_