The AIB was a multinational espionage organization that collected intelligence data; it was also effective in committing wholesale sabotage and creating impressive propaganda during World War II. Under the direction of U.S. General Douglas MacArthur, this agency was headquartered in Melbourne, Australia, and made up of five departments, including British and Dutch espionage, sabotage, propaganda, and the Australian Coast Watchers who operated in front of and behind Japanese lines. MacArthur left the Philippines in the Spring of 1942, ordered to Australia by President Franklin D. Roosevelt. His men on Bataan and Corregidor eventually surrendered to overwhelming Japanese forces but by that time MacArthur was building another Allied army in Australia in preparation of taking back from the Japanese the huge island-dotted area of the South Pacific they had engulfed in the first six months of the war. To accomplish this goal, MacArthur relied heavily on the AIB which was commanded by Colonel C.G. Roberts, head of Australian intelligence. Thousands of special volunteers served as Coast Watchers. They infiltrated Japanese-held islands and sent back reports to AIB visa short-wave radios. Using these reports, AIB commandos mounted devastating sabotage raids preceding MacArthur's northern advance from Australia to New Guinea and the many islands conquered by U.S. and Australian troops from 1942 to 1945.

During MacArthur's brilliantly conceived island hopping campaigns, AIB maintained constant propaganda through radio programs, clandestine presses behind enemy lines and leaflets dropped by airplane to discourage Japanese troops and inspire the conquered island peoples to conduct savage guerrilla activities against their Japanese foes. The AIB-directed guerrilla movement in the Philippines was particularly effective in disrupting Japanese communication., destroying ammunition depots, ambushing small Japanese contingents, and gathering intelligence on troop dispositions and available landing areas which helped MacArthur immensely in mounting his 1944 invasion of the Philippine Islands at Leyte. Once the Philippines were secure, the AIB went out of existence.

As another European war loomed in the late 1930s, fears of fascist and Communist “Fifth Columns” in America prompted President Franklin D. Roosevelt to ask for greater coordination by the departmental intelligence arms. When little seemed to happen in response to his wish, he tried again in the spring of 1941, expressing his desire to make the traditional intelligence services take a strategic approach to the nation’s challenges—and to cooperate so that he did not have to arbitrate their squabbles. A few weeks later, Roosevelt in frustration resorted to a characteristic stratagem. With some subtle prompting from a pair of British officials—Admiral John H. Godfrey and William Stephenson (later Sir William)—FDR created a new organization to duplicate some of the functions of the existing agencies. The President on 11 July 1941 appointed William J. Donovan of New York to sort the mess as the Coordinator of Information (COI), the head of a new, civilian office attached to the White House.

The office of the Coordinator of Information constituted the nation’s first peacetime, nondepartmental intelligence organization. President Roosevelt authorized it to collect and analyse all information and data, which may bear upon national security: to correlate such information and data, and to make such information and data available to the President and to such departments and officials of the Government as the President may determine; and to carry out, when requested by the President, such supplementary activities as may facilitate the securing of information important for national security not now available to the Government. COI, said historian Thomas F. Troy, was “a novel attempt in American history to organize research, intelligence, propaganda, subversion, and commando operations as a unified and essential feature of modern warfare; a ‘Fourth Arm’ of the military services.” The office grew quickly in the autumn before Pearl Harbour, with Donovan cheerfully accumulating various offices and staffs orphaned in their home departments.

One of Donovan’s hand-me-down units brought to COI a mission unforeseen even by him: espionage. Donovan had intended the clandestine intelligence gathering of his office to serve its analytical and propaganda branches; he had not originally sought to duplicate the foreign intelligence missions of the armed services. Nevertheless, it was the armed services, uncomfortable with the peacetime espionage mission, that persuaded COI in September 1941 to accept the small “undercover” intelligence branches of ONI and the G-2. Along with this acquisition, COI won authority to utilize “unvouchered” funds from the President’s emergency fund. Unvouchered funds were the lifeblood of clandestine operations. They were granted by Congress to be spent at the personal responsibility of the President or one of his officers, and were not audited in detail—Donovan’s signature on a note attesting to their proper use sufficed for accounting purposes. These funds, combined with the espionage authority granted COI by the military, planted the seed of the modern CIA’s Directorate of Operations.

Donovan recruited Americans who travelled abroad or studied world affairs and, in that age, such people often represented “the best and the brightest” at East Coast universities, businesses, and law firms. As war against Hitler loomed, not a few of America’s leading citizens looked for opportunities to join the struggle against Nazism. (COI’s successor, OSS, eventually drew such a high proportion of socially prominent men and women that Washington wits dubbed it “Oh So Social.”) These recruits brought into COI the practices and disciplines of their academic and legal backgrounds.

Donovan himself had travelled widely since his Army service in World War I, and he had been a careful observer of social, political, and military conditions. Similarly, his legal briefs on behalf of corporate clients were patiently and voluminously documented. As Coordinator of Information, he saw an opportunity to make research a cornerstone of his new information agency. Donovan won cooperation from the Librarian of Congress (the poet Archibald MacLeish) for his plan to analyse Axis strengths and vulnerabilities. At roughly the same time, COI established its own Research and Analysis Branch (R&A) to test Donovan’s hypothesis that answers to many intelligence problems could be found in libraries, newspapers, and the filing cabinets of government and industry. By autumn 1941, Donovan was proudly submitting the first of R&A’s meticulously prepared studies to President Roosevelt. The Branch was still small and focused on Europe at the time of Pearl Harbour, however, and it had no role in the operational and intelligence failures surrounding that disaster.

The Special Operations Branch (SO) of OSS ran guerrilla campaigns in Europe and Asia. As with many other facets of OSS’s work, the organization and doctrine of the Branch was guided by British experiences in the growing field of “psychological warfare.” British strategists in the year between the fall of France in 1940 and Germany’s invasion of the USSR in 1941 had wondered how Britain—which then lacked the strength to force a landing on the European continent—could weaken the Reich and ultimately defeat Hitler. London chose a three-part strategy to utilize the only means at hand: naval blockade, sustained aerial bombing, and “subversion” of Nazi rule in the occupied nations. A civilian body, the Special Operations Executive (SOE), took command of the latter mission and began planning to “set Europe ablaze.” This emphasis on guerrilla warfare and sabotage fit with William Donovan’s vision of an offensive in depth, in which saboteurs, guerrillas, commandos, and agents behind enemy lines would support the army’s advance. OSS thus seemed the natural point of contact and cooperation with SOE in combined planning and operations when the Anglo-American Combined Chiefs of Staff decided in 1942 that America would join Britain in the business of "subversion."

The Special Operations Branch served as SOE’s American partner. Together, SO and SOE created the famous “Jedburgh” teams parachuted into France in the summer of 1944 to support the Normandy landings. Jedburghs joined the French Resistance against the German occupiers. There were 93 three-man teams in all, each of them with two officers and an enlisted radio operator. Typically an OSS man would serve with a British officer and a radioman from the Free French forces loyal to General Charles de Gaulle. Trained as commandos at SOE’s Milton Hall in the English countryside, they were a colourful and capable lot that included adventurers and soldiers of fortune, as well as author Stewart Alsop and future Director of Central Intelligence William Colby. Officers trained alongside enlisted men in informal camaraderie because, once inside France, rank would have to be secondary to courage and ability. After landing (hopefully into the arms of the Resistance) the teams coordinated airdrops of arms and supplies, guided the partisans on hit-and-run attacks and sabotage, and did their best to assist the advancing Allied armies.

Significant parts of OSS’s paramilitary and psychological capabilities worked outside of the Special Operations Branch. In late 1942, the Joint Chiefs of Staff authorized OSS to run American commando units behind enemy lines. OSS promptly formed several “Operational Groups” to conduct these missions. These were small formations of specially trained US Army soldiers—many recruited from ethnic communities in America—who fought in uniform and had no obvious connection to OSS (so they would be less likely to be shot as spies if captured). Designated the 2671st Special Reconnaissance Battalion, Separate (Provisional) in 1944, Operational Groups fought in France, Italy, Greece, Yugoslavia, Burma, Malaya, and China, usually alongside partisan formations.

The Morale Operations Branch (MO) split from SO in 1943 to perform the “black” propaganda mission left behind in OSS when COI had been split the previous year. “Black” propaganda was supposed to look like it came from Germans or Japanese who were disgruntled with the war. It was intended to lower the morale of Axis troops and increase civilian resistance to the regimes in Berlin and Tokyo. In yet another example of the ways in which OSS organized itself to mirror British agencies, MO paralleled and worked with the Foreign Office’s Political Warfare Executive. MO took more than a year to find its niche in OSS and the Washington wartime bureaucracy, but by mid-1944 it was functioning effectively. Eventually MO’s early critics came to value its services, which included rumours about Hitler’s health and sanity, vast quantities of subversive leaflets, stickers, and slogans, and fake German newspapers and radio broadcasts (featuring, for instance, Marlene Dietrich singing “Lilli Marlene”). By the end of the war, MO and its companion civilian and military agencies had convinced policymakers in Washington that modern wars need to be fought in the "psychological" as well as military and economic arenas.