This thesis intersects the literatures of critical security studies and material semiotics to explore the operation of the US military, and through it, the operation of contemporary security agendas. Based around fieldwork conducted with 1st Cavalry (US Army) after its deployment in Operation Iraqi Freedom Phase II, this thesis argues for the exploration of security studies through the spatial operation of violence. Emphasising spatiality, it is argued, allows for an openness - and uncertainty - in accounts of security that can otherwise see violence as overdetermined. This thesis demonstrates this uncertainty - this experimentalism -in two respects, exploring both 1st Cavalry's embrace of ontological multiplicity as part of its operation in Iraq, as well as the continuing interference of multiple modes of absence and presence in enacting military units in the battlespace. The thesis concludes by arguing for more detailed attention to be paid to violence that emphasises its obstinate, reversible, and ultimately experimental nature.