In time, all the hard work led to the growth of the OSS into an organization with over 13,000 staff and 40 offices scattered across the world. Its purposes were initially similar to that of Britain's Special Operations Executive, including espionage, sabotage, and intelligence assessments, but with time and experience, it expanded to include economic, psychological, and guerrilla warfare, as well as counter-intelligence work. And of course, it would all chart a path for the early days of America's most famous intelligence agency, the CIA. The 28-year period from 1933-1961, bracketed on one end by Hitler's rise to power in Germany and on the other by the very height of the Cold War, was marked by a remarkably stable succession of American presidents. In fact, only three men held office in this period, and that predictability led to a general stability among government agencies. The CIA had five different directors in its first 15 years, from 1946-1961, but nine different directors in the next 20, with four of those directors serving less than a year. Although plagued by its own share of problems in its early existence during World War II and the early Cold War years, the agency's early problems, smoothed over by a string of tenured presidents, paled in comparison to those it would face in the coming decades. Through the 1980s and 1990s, presidential terms regained a measure of predictability, but the agency continued to struggle through the traps it had set for itself in the prior decades while trying to find its place in the new world of computers, 24 hour news coverage, and the sheer avalanche of information that came with technological advancements. When the Soviet Union collapsed in 1991, it appeared the CIA might no longer have an adversary formidable enough to keep the agency funded and staffed, but 9/11 ended that fairy tale and brought the CIA's next era into sharp focus.