THOUSANDS of people descended on Moscow, Washington, Paris, and London on Thursday. They came for one reason: to give hope to Syria, as the country entered the fourth year of war.

The #WithSyria event was marked in London in Trafalgar Square. Hundreds of people watched as messages of hope and solidarity for Syrians were projected on to Nelson's Column, and the voices of Syrian children were played to a soundtrack written by the band Elbow.

The global campaign was organised by a coalition of 115 aid agencies and charities to mark the third anniversary of the beginning of the conflict, and to remind the world that the suffering in Syria continues.

Speaking to the crowds in Trafalgar Square, the Lebanese-born comedian and broadcaster Dom Joly said: "We are here to celebrate a terrible anniversary - three years of unrelenting horror and misery for the Syrian people. Our message is 'Don't let the people of Syria lose another year to bloodshed and suffering.'"

Speaking before the event, Mr Joly said he did not know what the #WithSyria campaign could achieve, but that he had to do something.

"Who knows what it's going to do, but it's better than doing nothing," he said. "News cycles can move on, and [Syrians] can slightly think that they have been forgotten. And I think it's really important that they know they are not."

Candles marked out a map of the world on the ground as the words "Stand with Syria" and "Give hope" were projected on to Nelson's Column. Tweeted messages of solidarity and support were also added to the light display, as simultaneous #WithSyria meetings took place across the world.

Speaking at the event, aid-agency experts gave a downbeat assessment of the situation for Syrians.

The emergency field director for the International Rescue Committee, Sanj Srikanthan, said: "Syrians are a lot like you and me - they had middle-class lives - lives you could recognise - but now they are living in tents. The lack of dignity, the humiliation, the attacks and torture they faced in Syria is at a shocking level after three years.

"Most of the armed actors inside Syria couldn't care less for the majority of unarmed civilians, women, and children, who are caught in the middle.

"The incidence of violence against women is truly shocking - I have been doing this for six years, and I have never seen anything like it. It doesn't look like it's anywhere near stopping."

The head of Christian Aid's Middle East programmes, Janet Symes, said that Syrian refugees wanted jobs to sustain them rather than food handouts.

"It's very difficult expecting [the host countries] to provide jobs," she said. "Lebanon has about 900,000 refugees, but a population of just over four million; so providing jobs for the refugees will have an impact on the jobs for the Lebanese. It's important to work together and provide assistance to both."

But, she said, there was also the urgent problem of getting humanitarian assistance to Syrians trapped inside the country.

"The UN estimates [that] about 9.5 million people in Syria are in desperate need of humanitarian assistance - nearly 50 per cent of the population. There are still 240,000 people in besieged areas where aid is not getting in."

The chief executive of World Vision UK, Justin Byworth, had just returned from a visit to Zaatari refugee camp in Jordan, which now houses almost 100,000 men, women, and children who have fled Syria.

"I have a panoply of individual stories of real horror," he said, "and every single one has a story of such tragedy that when you put them all together and you think about the scale of it. . ."

One man told Mr Byworth how he had fled Syria after a soldier had put a rifle to the head of his ten-year-old son. The soldier then murdered a child who lived next door, before gouging out the eyes of the child's disabled father.

"This is the thing that I heard time and time again, especially from dads and mums," he said. "You ask Syrians 'What do you want us to do?', and they said: 'Tell our stories; don't let people forget us.'"

Nevertheless, Ms Symes said that she remained optimistic that things could change. "What's so important about this event is that it shows the people of Syria that people across the world care about them, and are standing with them.

"It also shows to governments around the world that they need to keep up the diplomatic engagement and keep pushing to find a political solution to the crisis."