Recent research has highlighted the mobilization potential of social media, which can offer citizens who were previously motivated to hide their true preferences an easier way to share their grievances and find common support. However, it is not clear how these changing dynamics of revealing preferences affect contentious processes beyond initial mobilisation. We argue that in conflict settings, previously shared social media posts indicating political loyalties can pose a severe risk for civilians. For example, anti-regime messages or display of digital support for the opposition may prove to be life-threatening in government controlled areas. Civilians are likely to strategically alter their social media usage with changing local dynamics of conflict. Drawing on the Twitter activity of users inside Syria between 2013 and 2016 we show how the creation of new accounts and the deletion or disuse of old accounts is empirically linked to changes in territorial control by the armed groups operating across Syria. The findings have important implications for our understanding of the risks - and the potential for civilian agency - when using digital communication in civil conflict.