But Bismarck thought colonies were pointless and a waste of money. There's reason to believe, if you read Britain's reports on its possessions in West Africa and what not, that Britain felt the same way towards many of them. I mean the established powers couldn't have been too stifling if Belgium and Portugal were allowed to have possessions quite out of proportion with their power in Africa. As it was, Germany had Tanganyika, Rwanda/Burundi, Swahililand, the Kionga Triangle, Namibia and parts of Botswana, Cameroon, Togoland, New Guinea, and Samoa. Not exactly nothing. If they felt stifled, it would have far better to do battle for colonies in the colonial territories themselves than risk European-wide war. This, in fact, is essentially what kept the peace in Europe during much of the 19th century as well as after WWII (although they were no longer colonies, same principle). Germany had many opportunities to do just that, but remained passive. Germany remained neutral during the Boer war. They remained neutral during the Russo-Japanese war. They stayed out of Persia and Morocco, etc. They could have cause more trouble but they did not.
What *caused* the war in my view was a combination of the strategic encirclement of Austria-Hungary and the after-effects of the annexation crisis in 1908. Britain joined the Entente essentially to stave off pressure from France and Russia on their empire. Britain signed the Anglo-Russian convention to focus Russia's attention on Turkey and the Balkans instead of Afghanistan and India. The result was the expansion of the Balkan League, which was potentially drawing in the whole of the Balkans against Austria-Hungary. Furthermore French control of Morocco had pushed Italy to focus its attention eastward as well.
But while A-H was encircled, they had also enraged Russia with their conduct during the 1908 crisis over the Bosnia annexation. A-H needed great power approval for any kind of move like that, so they pulled a fast one on Russia, exchanging Bosnia for Russian use of the Bosphorus. But Russia had thought the annexation of Bosnia would take place sometime in the future, whereas it happened immediately, before Russia was able to consult France and Britain over the Straits. By the time Russia consulted Britain about the issue, Britain had refused to allow it because of the instability the Bosnian crisis caused. Russia then was forced to tell an incensed Serbia to back off of Austria-Hungary for now, so as to avoid war. However future promises were made that should Serbian interests be harmed by A-H in the future, Russia would be prepared to go to war. That's precisely what happened in 1914.