Belfast City Council voted in December 2012 to fly the union flag above City Hall on designated days rather than every day. In response, the Ulster People’s Forum was linked to a series of ‘flag protests,’ disrupting rush hour traffic across Northern Ireland and culminating in rioting in some areas. Many flag protests were organised on Facebook pages (e.g. Save Our Union Flag), which allowed sharing of information on upcoming demonstrations and discussion of issues (e.g. alleged heavy-handed policing). This paper presents a thematic analysis of comments on the two main flag protest pages in January 2013. Findings suggest that these pages not only provided a platform for those who supported the protests, but were also used by their opponents to challenge their views, with some trolling. Such Facebook pages function as a space in which moderates on both sides of the sectarian divide can challenge the views of protesters.