Was the Buddha against violence in all situations?

  Is a strictly pacifist Buddhism exactly correct or are there certain situations were violence or war might be appropriate according to the Buddha's teaching?   What did the Buddha say about the Military?   Given that Buddhist countries have soldiers, what doctrine[s] do they use to justify having a military to defend the people and the Dharma?   Is there anything in the Tipitaka to support the idea that a soldier  who selflessly tries to defend others and/or the Dharma by violent means, makes good karma?