The Bush-Dulles relationship goes back to 1934, when a congressional investigation revealed that the Hamburg-Amerika shipping line, owned by Prescott Bush's father-in-law, Herbert W. Walker, was a cover for I.G. Farben. Prescott Bush hired Allen Dulles to conceal the assets, and Dulles continued working as a lawyer for Bush in his dealings with German firms through the 1930's. Although Bush eventually got into a certain amount of trouble for his Nazi connections, Dulles saw to it that after World War II Bush got his Farben shares back and was able to sell them. Bush and Dulles remained close through the 50's, when Bush was a senator from Connecticut and Dulles was first deputy director (1951) and then director (1953-61) of the CIA.
There are implications in "George Bush: The Unauthorized Biography" that George H.W. Bush may have been involved with the CIA as early as 1954:
"{George H.W.} Bush and the Liedtke brothers now concluded that the epoch in which large oil fields could be discovered within the continental United States was now over. Mammoth new oil fields, they believed, could only be found offshore, located under hundreds of feet of water on the continental shelves, or in shallow seas like the Gulf of Mexico and the Caribbean. By a happy coincidence, in 1954 the US federal government was just beginning to auction the mineral rights for these offshore areas. ... Bush and his partners therefore judged the moment ripe for launching a for-hire drilling company, Zapata Offshore, a Delaware corporation that would offer its services to the companies making up the Seven Sisters international oil cartel in drilling underwater wells. 40% of the offshore company's stock would be owned by the original Zapata firm. The new company would also be a buyer of offshore royalty leases.
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"1954 was also the year that the US overthrew the government of Jacopo Arbenz in Guatemala. This was the beginning of a dense flurry of US covert operations in central America and the Caribbean, featuring especially Cuba.<snip>
"Counsel were listed {in 1956} as Baker, Botts, Andrews & Shepherd of Houston, Texas; auditors were Arthur Andersen in Houston, and transfer agents were J.P. Morgan & Co., Inc., of New York City and the First National Bank and Trust Company of Tulsa."
http://www.american-buddha.com/unauthor.bio.bush.8.htm"In a couple of years he got help from his uncle, George Walker, Jr., and Farish's British banker friends, to set him up in the oil property speculation business.
Soon thereafter, George Bush founded the Zapata Oil Company, which put oil drilling rigs into certain locations of great strategic interest to the Anglo-American intelligence community."http://www.american-buddha.com/unauthor.bio.bush.3.htm