It has been a bloody battle but the SDF has prevailed and the Islamic State fighters remain in only a few pockets of the city of Manbij: http://www.france24.com/en/20160809-us-backed-fighters-victory-islamic-state-group-syria-manbij-aleppo?
Here is the backstory of the Manbij offensive: https://en.wikipedia.org/wiki/Manbij_offensive_(2016)
Some recent history of Manbij (also known as Little London): http://www.telegraph.co.uk/news/2016/06/02/syrias-little-london-a-base-for-plots-against-west-us-says-as-fo/
