Long-simmering ethnic tensions between mainly Buddhist Sinhalese and largely Hindu Tamil minority led to the civil war.
The bankrupt country says it will reduce army personnel to 135,000 by next year and 100,000 by 2030.
The current crisis is a second blow to the Tamil population, already ravaged by the civil war’s final offensive.
It was the first-ever public event on the island where mostly majority ethnic Sinhalese memorialised the minority group.