CPT Cahill was a graduate of the University of Nebraska at Omaha . He received his commission as a Second Lieutenant of Infantry for ROTC in August 1999. His assignments included Infantry Team Leader and Squad Leader in the 7th Infantry Division, Fort Ord, CA; Squad Leader and Platoon Sergeant in 3rd BN, 325th Airborne Infantry Regiment, 82nd Airborne Division, Fort Bragg, NC; Rifle Platoon Leader, and Anti-armor Platoon Leader, 3rd BN 327th IN, 101st Airborne Division, Fort Campbell, KY; Ranger Platoon Leader, Company Executive Officer and BN Logistics Officer, 1st Ranger BN, 75th Ranger Regiment, Hunter Army Airfield, GA; Deputy S-3 for 3rd BDE, 3rd ID, FOB Warhorse, Iraq; and his most recent assignment was Company Commander, Baker Company, 1st BN, 15th Infantry Regiment, FOB Wilson, Iraq.

CPT Cahill's military education includes the Infantry Officer Basic Course, Infantry Captains Career Course, and the Combined Arms and Services Staff School

CPT Cahill's awards and decorations include the Soldiers Medal, Bronze Star with one oak leaf cluster, Purple Heart, Meritorious Service Medal, Army Commendation Medal with three oak leaf clusters, Army Achievement Medal with two silver oak leaf clusters, Afghanistan Campaign Medal, Iraq Campaign Medal, Global War on Terrorism Expeditionary Medal, Army Good Conduct Medal, National Defense Service Ribbon second award, Combat Infantry Badge, Expert Infantry Badge, Air Assault Badge,, Pathfinder Badge, Senior Parachutist Badge, Sapper Tab, and the Ranger Tab.

He is survived by his wife Mary, and their two children, Faith, 4, and Brenna, 3.