The occupation of the Taiwanese legislature nearly came more than five months ago, when the same student activists tried to enter the building during a rally, but were thwarted by police.
The students had for weeks been seeking a way to catapult their nascent Black Island Nation Youth Front and its mission of derailing the island's free-trade pact with the mainland to the forefront of public attention.
Despite holding several rallies, the youth front could not gain much traction. All that changed when the island's president, Ma Ying-jeou, decided his ruling Kuomintang party would seek to pass the deal before the legislative session ends in July.
The KMT announced last week the pact would not be given a line-by-line review by lawmakers, and the party would instead seek to ratify the agreement in its entirety.
Late on Tuesday, about 200 students slipped past security and took control of the chamber, where they have vowed to remain until their demands are met.
Chen Wei-ting, a student at National Tsing Hua University, and one of the group's leaders, said the occupation was the result of months of strategising.
Chen is no stranger to activism - he once threw his shoes at a local magistrate in protest over a local government land expropriation effort.
He helped to establish the youth front in September, drawing on unease in college campuses that enacting the deal would lead to fewer jobs, and give Beijing greater sway over the island's future.
On October 1, about two dozen members staged a protest outside the legislature and tried to find a way inside, but the rally broke up when police moved in and forcibly removed them.
Another rally near the Presidential Office on October 10, Taiwan's national day, ended in a similar fashion.
Key members of the organisation rethought their tactics. A plan was devised for students to divide into three groups and wait outside three side doors of the legislature, Chen said.
When police were called away to help control another protest at the front gate of the legislature on Tuesday, the students took advantage of the confusion and slipped inside the chamber.
Lin Fei-fan, one of the group's leaders, says their occupation was justified.
"Why did we do that?" he said. "It's all because we believe Ma Ying-jeou has already lost his right to act as the president, given his insistence on pushing through his will to have the legislature, dominated by his governing Kuomintang, pass the pact in June."
Lin, a student at National Taiwan University, also once initiated protests against a local news media outfit perceived as trying to monopolise the local market.
"We are also angry because Ma's governing Kuomintang went back on its word on Monday by sending the pact to the legislature for a floor review in its entirety instead of an itemised review as previously agreed," Lin said.
The front has come across as disciplined, said Hsu Yung-ming, an associate professor of political science at Soochow University in Taipei. Students formed a disciplinary committee to restrain others from growing violent or littering the legislature.
More than 100 professors have backed the students in what has been dubbed the "sunflower" movement. Several university departments have announced a temporary recess to allow students to join in the protest.
Hsu said the protesters' success was also due to "secret help from legislature speaker Wang Jin-pyng, who asked not to use police force to remove the students from the chamber".
Wang - one of Ma's main rivals within the KMT - has urged protesters to remain reasonable but says the occupation was the result of "someone who broke a promise", which was taken to be a reference to KMT lawmaker Chang Ching-chung, who announced the review reversal.
The protest has attracted attention from some Hong Kong activists who back the "Occupy Central" protest, planned for the city's downtown business area in July, over dissatisfaction with democratic reforms.
They have expressed solidarity with the Taipei students through written letters to the organisers and some have visited the protest site.
Huang Yu-feng, a spokeswoman for the youth front, said the students wanted Ma to make an apology and end the review of the agreement. "We also want that the legislature to institute a bill to oversee all agreements signed by Taipei and Beijing and that the Ma government not negotiate or sign any such agreements before the bill is approved," she said.