HONG KONG — In many places around the world, a single date marks seismic events considered turning points in recent history, like the Sept. 11 attacks in the United States or the Nov. 9 fall of the Berlin Wall for Europe. For post-colonial Hong Kong, the turning point fell on Aug. 31, 2014.

That was when a top Chinese government body announced a plan for limited democracy in Hong Kong. Beijing’s decision fell considerably short of what democracy protesters were demanding that summer, and it set off a two-month occupation of several Hong Kong neighborhoods that came to be known as the Umbrella Movement.

This year, demonstrators seized on that day — known simply as “the 8/31” — for what they hoped would be a huge march this Saturday, although an organized rally now seems unlikely.

The Hong Kong authorities have declined to grant the protesters a permit, raising the possibility of a repeat of recent clashes should the demonstration be held. The authorities rejected an appeal on Friday, and march organizers called off the demonstration after failing to win approval, although people are likely to protest in other ways.