18 March 1977
On 18 March 1977, Marien Ngouabi, the military President of the Republic of the Congo was assassinated.  Ngouabi, who started his career as the Commander of the first Paratrooper Battalion in the Republic of the Congo, rose to this position after the ousting of former President Massamba-DÁƒÂƒ©bat during a military coup in 1968. Initially Ngouabi appointed Alfred Raoul as Prime Minister, but after Raoul's reign proved unstable, in part due to Ngouabi purging any opposition to his reign. Ngouabi eventually assumed this position himself which he held from 31 December 1969 till 18 March 1977. It is speculated that Ngouabi was assassinated due to his unwillingness to collude with French authorities, who sought greater control over the oil rich Cabinda region of Angola and who urged Ngouabi to annex the region.  However, after his refusal to be part of this plot, they then conspired with opposition figures within the Congo to oust him from power.  After successive unsuccessful attempts, an alleged suicide commando managed to assassinate him. This act was followed by summary trials and executions of a number of political rivals judged to be behind the assassination. Among them was the former president Massamba-DÁƒÂƒ©bat.  
References

Aglobalworld, 'Republic of Congo Commemorates the Life of President Marien Ngouabi ( Marien Ngouabi Day)', [online], Available at aglobalworld.com [Accessed: 17 March 2014]|