Members of Jaysh al-Ummah have claimed that their group was founded in 2005. However, reseachers have dated its beginning instead to 2007 or 2008. Since its foundation, the group has mostly focused on shooting rockets and other explosives into Israeli territory. In January 2008, the group announced that it planned to murder United States President George W. Bush. On 1 September 2008, the group organized its first "public training session" in southern Gaza, using the opportunity to criticize Gaza's Hamas government. Two days later, Hamas arrested Jaysh al-Ummah's leader Abu Hafs al-Maqdisi, prompting the group to threaten violent responses unless their commander was released. Afterwards, the two sides became generally hostile, with Jaysh al-Ummah ignoring any ceasefire agreements agreed upon between Hamas and Israel, while Hamas would repeatedly arrest Jaysh al-Ummah members. However, the two groups refrained from open fighting. Jaysh al-Ummah fought in the 2012 Gaza conflict and the 2014 Gaza War against Israel.