They prepare for the possibility when going to war, but most military members don't expect to lose their lives here at home during training missions.
It seems to be happening a lot in the first half of 2013, especially with troops based in Virginia and North Carolina.
The first two came in February, when Navy Diver 1st Class James Reyher and Navy Diver 2nd Class Ryan Harris drowned during an underwater training exercise at Aberdeen proving ground in Maryland.
Two senior leaders from their unit, Mobile Diving and Salvage Unit two at Little Creek, are now facing possible charges of involuntary manslaughter and dereliction of duty.
Less than a month later, seven marines from camp Lejune in North Carolina died during a live fire training exercise at Hawthorne Army Depot in Nevada.
A mortar round exploded unexpectedly inside a firing tube and three officers from the unit were relieved of duty as a result.
And at the end of March, Brett Shadle, a member of Beach-based SEAL Team Six, was killed in a parachute accident when he collided in mid-air with another SEAL.
The two were performing military free-fall training at Pinal Airpark in Arizona.
The most recent death was last Wednesay when a Humvee flipped during convoy training at Fort Knox, killing 23 year old navy seal Jonathan Kalousth.
Stationed at Little Creek with Naval Special Warfare group two, the commander has now launched an investigation into what happened.