Recently, whilst teaching university students, I was asked on numerous occasions if a Buddhist can become a solider. At first glance you would think not, because one of the five precepts states that we should refrain from killing. Also one of the five inappropriate livelihoods says that dealing in weapons is wrong. However, Gautama Buddha seems to have made concessions on this point. In the Chakkavatti Sihanada Sutra he told a king that an army is justified as it offers protection and security for different classes of people in the kingdom from internal and external threats. Also in the Seeha Senapathi Sutra, whilst talking to an army officer called Seeha, he did not advise Seeha against the army or being a commander of an army, but only advised him to discharge his duties the proper way.
He did prohibit a solider from becoming a monk whilst still in military service. The story goes that his father came to him and complained that he had insulted him by begging for meals, walking house to house along the streets in his own town. He said his relatives laughed at him and they insulted him and now he was trying to destroy his father’s army. It seems that many soldiers where leaving the army to become monks because they received free food and shelter. So Gautama Buddha then promulgated a law (Vinaya) stating no soldier can become a monk.
So I think it is clear that contrary to the popular belief Gautama Buddha has not rejected or prohibited soldiering as a profession or occupation. He has instead recognised the necessity of an army to provide protection to the subjects of a country.
A final word on this topic. I do not want you to think Gautama Buddha thought war and killing was a good thing, he certainly did not. It states this in the Dhammapada:
Victory breeds hatred
The defeated live in pain,
Happily the peaceful live,
Giving up victory and defeat
Victory and defeat are two sides of the same coin of War.
So it isn’t as black and white as the list of five precepts and inappropriate livelihoods may suggest.