(CNN) The final days of the years-long battle for Aleppo are here. One by one, neighborhoods are falling to the Syrian regime, and those left behind face a variety of gruesome fates: Will they be trapped? Bombed? Or executed by government forces, as reports are suggesting?

The humanitarian crisis is immeasurable, and those inside and out of the city are wondering aloud why the world has seemingly abandoned the thousands of innocent people still caught in Aleppo's deadly snarl.

But it may not be fair to say that those looking on have always been indifferent. Throughout the struggle, the stories of the war's smallest victims have captured international attention. For those who couldn't fathom the suffering there, these were the moments when Aleppo became real.

The boy in the ambulance

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In August 2016, photos of a little boy, bloodied and covered in dust on the back of an ambulance, moved people to tears. His name is Omran Daqneesh, and days after the attack that destroyed his home, his 10-year-old brother Ali succumbed to his wounds.