The Geneva Accords incorporated as eries of carefully phased withdrawals and disengagement's to be monitored by an International Control Commission (ICC) formed from Polish, Indian and Canadian military contingents. Even before the document was signed, French forces in North Vietnam had begun pulling back to their final positions around Hanoi and Haiphong. The victorious Vietminh did not enter Hanoi until 9 October and the French held the port of Haiphong until May of 1955. In the interim, U.S. agents of the new Central Intelligence Agency (CIA) went to work behind French lines, spreading propaganda and sabotaging equipment shortly to fall into the hands of the victorious Vietminh. Perhaps their most noteworthy success was persuading Catholics to flee to the south; of the 860,000 or so people who fled the north, as many as 600,000 were Catholics. In the south, Vietminh cadres went underground or moved north as religious sects, nationalists and Bao Dai adherents scrambled for power, fighting across a political landscape that bore the imprint of seven decades of divisive French policies. The onset of total chaos was arrested by the appearance on the scene of one of the strangest political leaders ever to walk the stage of history, Ngo Dinh Diem.
The son of a councillor to Bao Dai's father, Emperor Than Thai, Diem received a French education and served briefly in the French colonial government during the early 1930s before resigning in protest over the French refusal to grant meaningful power to Vietnamese officials. A political activist and an ardent nationalist, Diem had refused an offer to serve in the Japanese puppet government in 1945. A devout Catholic and a staunch anti-communist, he subsequently rejected a similar offer by Ho Chi Minh. But Diem's family was large, powerful and well-connected - his elder brother Ngo Dinh Thuc had entered the priesthood and risen to the position of Bishop of Vinh Long in South Vietnam - so Diem was not without supporters or resources. In 1950, and still a relative unknown, he traveled to the United States, where he met numbers of influential Americans including Francis Cardinal Spellman and senators John F. Kennedy and Mike Mansfield. When, during the 1954 Geneva negotiations, he accepted Emperor Bao Dai's offer to become Prime Minister of what was to be the Republic of Vietnam, he quickly demonstrated surprising willpower along with a good measure of luck-aided by American support at several critical junctures - in consolidating his power.
In a series of astonishing political twists and turns, between the Geneva Accords and the fall of 1955, Diem became the unchallenged political leader of South Vietnam. With the assistance of well-timed Saigon street demonstrations orchestrated by his younger brother Ngo Dinh Nhu, he convinced the Americans that he was a credible national leader, insuring the indispensable sanction and support of the United States. Diem's first serious challenge came from the French-backed Binh Xuyen, who controlled Saigon's gambling and vice syndicates and maintained a sizeable private army. Bolstered by American Air Force Colonel Edward Lansdale, he ordered the nascent South Vietnamese Army against the Binh Xuyen in April of 1955. To the astonishment of informed onlookers, the ARVN (Army of the Republic of Viet Nam) defeated the Binh Xuyen in a series of battles that left 500 dead and thousands homeless. By May, Binh Xuyen leader Bay Vien was in exile in Paris and the remnants of his forces had fled to the Mekong Delta where they joined the Vietminh. Even before his destruction of the Binh Xuyen, Diem had begun to move against the religious sects, the Hoa Hao and Cao Dai. With a combination of military force and police state coercion, orchestrated by his younger brother Ngo Dinh Nhu, he succeeded in neutralizing them politically and incorporating their militias into the ARVN. Finally, in a blatantly rigged national election, Diem forced the electorate to chose between him and the discredited Bao Dai.
Ngo Dinh Diem's assumption of the Presidency on 26 October, 1955, marked the birth of the Republic of South Vietnam, and even his detractors had to admit that he had demonstrated amazing staying power. The execution of imprisoned Hoa Hao leader Ba Cut and the departure of the last French troops the following April seemingly put the seal of permanence on his regime. Following his victory over the sects, Diem moved against Vietminh remnants and revolutionary opponents with his To Cong ("Denounce the Communists") campaign which, in prevailing turmoil, achieved some considerable success in rooting out Vietminh cadres. Diem also achieved a rare victory over the communists in the war of ideas by successfully labeling the southern communists VietCong. A derogatory appellation meaning Vietnamese Communist. He petitioned President Eisenhower for military assistance and advisors; advisors came, teaching their Vietnamese charges the complexities of weapons systems, and the skills required to operate them, along with organizational schemes and tactics. Some few of them came to appreciate the political complexities of the situation in which they found themselves. What they did not do was to communicate that appreciation successfully to their military and political superiors.