Enjoying a production run that spread out over 14 years, over 290,000 of these machines were produced. Around 1940, the cost of the Farmall M was around $1,100. The cost of the Farmall MD was around $1,700. Many of the Farmall M tractors are still in use today, and parts are readily available. As far as collectability, these are the least popular of the letter series, most likely due to their large size.
The reason for rules in war is simple: people value life. The rules of war are mostly about giving people a way to lose without dying. Rules, such as the use of a white flag, give people a way to surrender. Bans on chemical and biological weapons prevent indiscriminate and uncontrollable killing. And rules protect POWs.
The rules of war do not apply to every act of hostility against an established government. Openly declared wars between sovereign states clearly implicate the rules of war. When the belligerents do not issue formal declarations of war, the legal status of a military conflict becomes murky.