The key to deciphering this line is the sentence right before it and the clause after it:

England has a conspicuous advantage over other nations in that her soldiers have the best of all training grounds. France and Germany may be at peace with all the world for many years, but scarce a year passes in which England has not had an encounter with some hill tribe, or is not called upon to defend her frontiers in the distant East.

The article itself is a review of George Forrest's Sepoy Generals, a very typical turn of the century history of the Britain's heroic generals in India.

Now the author of the review is not saying that German-French relations are at a moment of peace. Quite the opposite. The article is implying that the two countries on the continent are the two armed camps. But like a camp, these two militaries are not fighting but preparing to fight for a war. The author's use of "may" is instructive in that it implies that war might not come. In contrast, the British military experience is one of constant fighting with "hill tribes" but this was no less of a martial contest than the two countries eyeing each other.

This is the framing for the favorable review of Forrest's book. The Spectator's author is likely not expecting pacifism and demilitarization to break out on the continent. Instead, he was drawing a comparison between the continent's dormant armed camps and the fact that Britons have been fighting real wars that educated great generals like Wellington.