What is expeditionary affairs in this context?

Question

So it seemed to us. It was an agreeable and therefore a readily acceptable idea. We imagined the Franco-German War of 1870-71 and the Russo-Turkish War of 1877-78 were the final conflicts between Great Powers, that now there was a Balance of Power sufficiently stable to make further major warfare impracticable. A Triple Alliance faced a Dual Alliance and neither had much reason for attacking the other. We believed war was shrinking to mere expeditionary affairs on the outskirts of our civilisation, a sort of frontier police business.

-The New World Order by HH. G. WELLS

I do not understand what did the author mean by "expeditionary affairs" and "frontier police business".

According to Cambridge dictionary "expeditionary unit" means :

a group of soldiers sent to another country to fight in a war

And about "frontier police" I am confused.

As a verb police is (Cambridge dictionary): to control or guard a public event or area by using members of the police or a similar force.

But also it has a meaning as a noun. I don't know which one to choose.

Answer 1

We must read this in its own context, and in the context of the time it was written.

Wells tells us that by 1878 it was thought that major wars between European nations had ended, and that wars were mostly small scale actions between European nations and countries outside of Europe. By "expeditionary affairs", Wells is thinking of actions like the Boer wars in Africa, or various actions against uprisings in India. In these cases the war was fought by an expeditionary unit. And rather than being a battle within Europe, they were aimed at maintaining control in the territories that European countries had colonised. Rather than being wars of conquest, they were more like "police business" in that they were about controlling a population (in Africa or India, for example)

The irony is that Wells knows that by 1914 Europe was at war with itself again as it was in 1940 when the book was published.

Answer 2

"Expeditionary" means relating to an expedition.

Expeditions are like 'fact-finding' missions, as opposed to offensive military missions which involve or anticipate conflict. The word "expedition" is used widely outside of the military context, for example, scientific expeditions to the polar regions.

The suggestion of your text is that the conflict had gone out of the war and that military personnel had been "reduced" to those kind of missions, rather than engaging in conflict. That it likens it to a "policing" suggests that they had achieved a level of peace and were now trying to maintain it.