Brutal, horrific and sudden - as the sheer horror of Syria's civil war is captured in a series of powerful images by Tracey Shelton, Channel 4 News looks at iconic war images of past conflicts.

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Every war has its iconic images that somehow seem to capture the whole of a conflict and become forever associated with it.

Tracey Shelton, a correspondent for the world news site Global Post, captured a series of photos in the northern city of Aleppo earlier this week. Seven frames depict tank fire which killed three rebel fighters - the images are now reverberating around the world.

The Australian photographer's images will forever be associated with the civil war in Syria.

Picture gallery: Tracey Shelton's photos from the frontline in Syria

From the innocuous first image, through to the almost surreal celestial lit moment of impact, and on to the shock and raw grief of the final image, these seven images tell a simple but terrible story.

Debate still surrounds Robert Capa's infamous "Falling Soldier" which he claimed was the moment a militiamen was shot in the Spanish civil war, but the image is the best known from that war.

In Vietnam many images came to symbolise the war but three- Eddie Adam's photo of a bound prisoner being executed by a south Vietnamese officer in the street, the little Vietnamese girl Kim Phuc running from a napalm attack and Don McCullin's photo of a shell shocked soldier will all forever be associated with that war.