bought the farm in the World War II为什么会翻译成阵亡?

buy the farm[美俚]阵亡；买下农场（死了）；突如其来的不正常死亡
关于来源,因为是美国的俚语,只有美国人比较清楚,下面是几个外国人的解释,我翻译了认为最可能的.
1.Buy the farm was originated with pilots.Mostly military.
If something from the government crashes on to a farm - like a military plane,the government 'buy the farm'.as in the land that it destroyed.The pilot is dead because of the impact...
“Buy the farm”的起源来自于飞行员.主要指军方的飞行员.如果*部门的某件东西撞毁在农场里——例如军用飞机,*部门就会“买下那个农场”,因为那块地已经被破坏了,而飞行员也在撞击的过程中死了…….
所以“Buy the farm”就比喻突如其来的不正常死亡,也就是阵亡了,特别是在战争中的,像第二次世界大战等.
2.To die,espescially in combat; most likely from the idea that a dead soldier's death benifit would serve to pay off his family's morgtage.Often shortened to "bought it."
3.This term was used during World War 2 whenever a Allied Pilot would have to make a crash landing into a European farm/house.WW2 pilots who did this were actually charged for the damages they caused and actually in a sense:"bought the farm"