1974- 2003-2011 21stcentury american american-military american-sniper autobiography biography book:sgakyl chris chris-kyle collegesuccess combat deadliest-sniper english heroism history iraq-war iraqwar iraqwar(2003-) kyle memoir mental-health military military-history military-tactics militaryhistory modernhistory navy-seal patriotism personalnarratives sniper-rifle snipers socialsciences true-story unitedstates veteran war