Columbia, as all countries in the world, has its own government which is responsible for controlling the country. If the government comes into a situation where it is not able to control the country, or it has been overthrown so there's no government in place, second in charge is the military. The military is the one that will have the obligation of keeping things under control in Colombia in a non-government situation, as that is what the legislative says. In practice that will be incredibly hard though, as the drug cartels in Colombia are very powerful, so there's every chance that they will be able to take over whole regions of the country, or even all of the country in a scenario like that.
In WW1 Japan was a growing empire trying to take more land and get more resources to become a world power. Imperialism is the main reason they entered WW1.
I've added the web site in the image since it will effect my answer and make it get deleted. Its a safe website. It includes several stories of peole who went through the war. Most of them are secondary, few of them are primary sources.
