The flag of the Colonial Annam West's involvement in Vietnam dates back to
166 BC with arrival of merchants from the Roman Empire , 1292 with the visit of Marco Polo and the early 1500s with the arrival of Portuguese and other European traders and missionaries Alixendre the Rhodes, a French Jesuit Priest improved on earlier work by Portuguese missionaries and developed the Vietnamese Romanised alphabet in 1651.Nguyen Dynasty
After Nguyen
Anh established the Nguyen Dynasty in 1802, he tolerated Catholicism and employed some Europeans in his court as advisors.However, he and his successors were conservative Confucians who resisted westernisation. The next Nguyen Emperors, Ming Mang Thiu Tri and Tu Duc brutally suppressed catholicism and pursued a closer door policy, perceiving the westerners as a threat.Tens of thousands of Vietnamese and foreign born Christians were persecuted and trade with the west slowed during the period.These acts were soon being used as excuses for France to invade Vietnam.Actually, the early Nguyen dynasty accomplished almost everything the previous great Dynasties did excepts those fits were not enough in the new age of science , technology, industrialisation, trade and politics.The Nguyen dynasty was usually blamed for failing modernize the country in time to prevent French colonisation in the late 19th century.Under the orders of Napolean II of France, the French gunships under Reault De Genouilli attacked the port of Da Nang in 1858, causing significant damages, yet failed to gain any foothold. De Ganouilli decided to sail south and captured the poorly defended city Gia Dinh (present day Saigon). from 1859 to 1887, French troops expanded their control over all provinces on the Mekong Delta and formed a French colony known as Cochin China. A few years later French troops landed in Northern Vietnam (which they called Tonkin) and captured Ha Noi twice in 1873 and 1882. The French managed to keep their grip on Tonkin although twice, their top commanders, Francis Garnier and Henry Rivieire were ambushed and killed.France assumed control over the whole of Vietnam after the Franco-Chinese war (1884-1885). French Indo-China was formed in Oct 1887 from Annam(central Vietnam).
In the early 20th century, the Vietnamese patriots realised that they could not defeat France without modernization. Japan served as a perfect example that modernization could help an Asian country to defeat European Empire.
Marxism was also introduced in Vietnnam. with the emergence of three Communist parties (Indochinese Communist Party, Annamese Communist party , and Indochinese communist Party). and later a Trotskyist movement led by Ta Thu Thau. The Commintern sent Nguyen Ai Quoc to coordinate the unification of the parties into the Vietnamese Communist Party in 1930, in Hong Kong, with Tran Phuas the first general Secretary. Later the party changed the name to Indochinese Communist Party as Comintern, under Stalin, did not favor nationalist sentiments.Nguyen Ai Quoc was a leftist revolutionary being ib France since 1911. He participated in founding the French Communist Party and in 1924 travelled to the Soviet Union to join the Communist International (Comintern).Though the late 1920s he acted as a Comintern agent to help communist movements in South East Asia. During the 1930s, the Vietnamese Communist Party was nearly wiped out under french suppression with the execution of top leaders such as tran Phu i,e,, Hong Phong and Nguyen Van Cu in 1940.during World War II. Japan invaded Indochina and kept the French Govt as a puppet Govt. 
