Koreans today mark the troubled birth of their divided nation 

The movement quickly spread to cities and town across the peninsula. About 2 million Koreans answered the call, making up 10 per cent of the population at the time. Overwhelmed by the size of the protests, Japanese authorities used troops to suppress the movement, resulting in thousands of deaths. 
The uprising led to the founding of the Provisional Government of the Republic of Korea in Shanghai. The provisional government went unrecognised by major powers at the time, but it sponsored armed resistance to Japanese rule. Founded in 1948, the Republic of Korea drew on the Provisional Government for its legitimacy. Today, the anniversary of the movement is a national holiday and the signatories of the Korean Declaration of Independence are remembered as national heroes.
The March 1 Movement left other important legacies. In the long sweep of Korean history, it was the first nationwide popular rebellion against an authoritarian government. Previous rebellions were peasant uprisings that were typically local and limited in their scope. The Donghak Peasant Revolution from 1894-95 was a nationwide armed rebellion led by followers of the pantheistic Donghak religion, but it was closer to a guerrilla war than a popular rebellion. 
The 1960 April Revolution, pro-democracy protests from 1979-80, and the candlelight protests of 2017 looked to the March 1 Movement for inspiration. The uniting idea is that people should take to the streets to oppose a repressive and unjust government. The candlelight protests of 2017 occurred 30 years after democratization began, so their focus was more on the weakening of democracy under President Park Geun-hye. The tradition of taking to the streets to challenge the government enriches Korean democracy by creating a “citizens’ check” on government power.
Another important legacy of March 1 is Korean nationalism. The Donghak religion was based on Neo-Confucianism, but also drew on Shamanism and Buddhism. The stated goal of its followers was to resist Christianity and foreign influences by turning Korea into a “paradise on earth” where people were free and equal. In 1905, Son Byong-hi, the third leader of the Donghak faith, codified the religion and changed its name to the present-day Cheondogyo. Son was a leader in the independence struggle, and 15 of the 33 signatories of the Independence Declaration were members of Cheondogyo.
A consistent element of Korean nationalism is resistance to foreign influence through an adherence to “purity”. After liberation, both Korean states adopted this ideology and appealed to Korean traditions for legitimacy. This streak is much stronger in North Korea and it informs much of North Korea’s state ideology and actions under the label “Juche”. It was strong in South Korea during the Park Chung-hee regime, but it has since faded as the country has transformed itself into a liberal democracy.
Still another important legacy of the March 1 Movement is unity and solidarity. In addition to Cheondogyo leaders, 16 protestant leaders and two Buddhist leaders, including the famous poet monk Han Yong-un, signed the Declaration of Independence. Despite the sharp differences in religious beliefs, the leaders came together in solidarity for the cause of independence.
Since then, rift and conflict have become the dominant narrative in the Korean peninsula, and the current division into two antagonistic states continues to reinforce this narrative. In South Korea, unity of purpose propelled the two historical projects – economic prosperity and democracy. Much of the success of the 1988 Seoul Olympics and the 2018 Pyeongchang Olympics came from a unity that came from pride in hosting these events. Meanwhile, the two Korean states have on rare occasions come together for a show of unity, the most recent of which was marching together at the opening ceremony of the PyeongChang Olympics.
For most Koreans, March 1 is just another holiday. But it marks a watershed moment in their history, when the first popular nationalistic movement asserted that Koreans had the right to define their nationhood on the global stage. Today, this may seem obvious, but the division of Korea into two states and the tension that the division creates are reminders of the continued influence of outsiders. This explains why, despite its historical importance, March 1 remains a complex and unfulfilled celebration. – The Korea Herald/Asia News Network

Robert J Fouser, a former associate professor of Korean language education at Seoul National University, writes on Korean issues from Pawtucket, Rhode Island.