One of the organisers, Seran Sribalan, said it was an emotional occasion.
"Four people who were there at the time have now come to Australia as refugees actually told their stories and it was horrifying to hear how they would see a drone come in that would take pictures and then two minutes later that exact place would get hit."
The conflict between the Sri Lankan Army and the separatists known as the LTTE lasted from 1983 to 2009, and is believed to have claimed the lives of up to 100-thousand people.
Mr Seran Sribalan said many civilians were killed:
"And those places were basically places where it was packed with civilians, in no-fire zones, or the hospitals or temples and churches."
Last night's event at the Bowman Hall in Blacktown aimed to pay tribute to those who died before the war ended on the 18th of May.
Sydney's Tamil community has used the event to call on Australia to boycott this year's Commonwealth Heads of Government Meeting (CHOGM) in, Colombo.
I think Australia should take a really strong stand. We're in the Security Council in the UN. We are an important nation. It's high time that we took a righteous stand and said, "look enough is enough." Mr Sribalan said
"We've really got to put pressure on Colombo to change its ways, for the sake of accountability, for the sake of human rights."
Canada has threatened to snub the November meeting, unless Sri Lanka investigates suspected war crimes committed by government troops during the 25-year conflict.
About a thousand Tamils gathered in Blacktown last night to pay tribute to the tens of thousands who died before the war ended in May, 2009