Because you could just sit in your trench and wait for the opponent to attack, at which point you could shoot him, throw explosive devices, or even use chemical weapons that weren't banned then.
European power of France, Britain, Belgium and Netherlands were keen to take advantage of Africa's abundant natural resources including Gold, Silver, Minerals and even Slave labor.
Similarly, the Japanese knew they lived in a small piece of land which was resource-poor and isolated from the rest of the world.
By expanding and colonizing Asian countries, they wanted to take advantage of local resources which including abundant food and millions of people as slaves.
Answer:
Philosophical method is the study of how to do philosophy. A common view among philosophers is that philosophy is distinguished by the ways that philosophers follow in addressing philosophical questions. There is not just one method that philosophers use to answer philosophical questions.
