Bangladesh, Sept. 23 -- A massive wave of anticorruption protests swept across Manila on September 22, exposing deep public anger over billions of dollars allegedly siphoned off from government flood-control projects. What began as a largely peaceful rally of tens of thousands quickly turned violent, leaving one dead, hundreds arrested, and hundreds more injured, underscoring the fragility of Philippine democracy amid intensifying scandals surrounding President Ferdinand “Bongbong” Marcos Jr.s administration.

The demonstrations followed revelations that nearly 10,000 government-funded flood-control projects, valued at more than $9.5 billion, are under investigation for corruption. These projects, carried out between July 2022...