The Great Meme War refers to the internet based war conducted by supporters of numerous presidential candidates of both parties from June 2015 to November 2016. During this time period users of social media, mostly from Reddit and 4chan, conducted numerous “operations” to sway the public opinion of United States citizens to assist their preferred candidate and their presidential campaign. Using internet memes, the groups involved were successful in starting numerous trends on social media sites like Facebook and Twitter.

Source: The Great Meme War – Encyclopedia Dramatica