For the British military, one more ruined Christmas should pose no hardship. From the Balkans and East Timor to Congo and Sierra Leone, the apostle of intervention, Prime Minister Tony Blair, offers their services and the international community eagerly accepts. Result: a peacetime Army operating at full stretch around the world. Some would say overstretch.

It’s all an echo of bygone days of empire, when Britain bestrode the world, exporting Eurocentric civilization and dashing hither and thither to put out colonial brush fires. Coupled with 30 years of street combat in Northern Ireland, it makes for a depth and breadth of expertise that NATO and the United Nations love to call on. A mere 850 British soldiers brought peace to Sierra Leone, helping to quell a brutal guerrilla army and sorting out the mess made by a mishmash of ineffective U.N. forces. It was the British who first volunteered to close the porous Kosovo border with southern Serbia and Macedonia in the summer’s latest Balkan war. According to U.N. insiders, it’s also the British who argue most strongly for “rolling up” the former leaders of the Kosovo Liberation Army who have turned to organized crime. In the flash-point city of Mitrovica, unarmed British troops have risked life and limb to stand between mobs of ethnic Serbs and Albanians, where the French (and even Americans) fear to tread. In the words of one British officer stationed in Kosovo: “We know how to do this. We are willing. We are able. No one else is.”

When Blair speaks with almost religious zeal about Britain’s role as a “force for good,” this is what he means. The questions are: How far can Britain go? Are there limits to what it can deliver, however willingly? Certainly, its Army is better equipped than many. Unlike Britain, most other EU countries depend largely on conscripts, who can serve overseas only as volunteers and generally lack the professionalism required of rigorous peacekeeping missions. (Witness the Netherlands and the heartbreak of Srebrenica.) Germany has yet to fully resolve the political and constitutional issues of placing its forces abroad in harm’s way. And only France can match Britain’s share of the budget devoted to national defense. “Britain is now the second most important military expeditionary power after America,” says Michael Clarke of the Centre for Defence Studies in London. Yet even those who applaud Britain’s new role worry that the tasks increasingly being asked are growing beyond the nation’s capabilities.

The new mission in Afghanistan comes at a time when, many say, resources are already fully extended. With 100,000 on the payroll, the British Army is at least 5 percent under strength. Some 13,000 troops are stationed in Northern Ireland; an additional 2,000 are garrisoning the Falkland Islands, 2,500 are peacekeeping in Kosovo and others are scattered around the world from Germany to Belize. Nearly a quarter of the British Army is now posted outside Britain–with all the consequent support and logistical costs.

Few openly challenge the government’s commitment to rebuilding Afghanistan. The debate is around the edges. Recently the chief of the Defence Staff, Sir Michael Boyce, came as close to overt criticism as military discipline allows. “We have to face the fact,” he said, “that our ability to run concurrent operations will be affected. Something will have to give.” It’s no accident that British military officials suggested recently that NATO should reduce its forces in Bosnia by a third (echoed by U.S. Defense Secretary Donald Rumsfeld) in order to free up resources elsewhere in the world.

Blair’s political opposition is also sounding warnings. Tory leader Iain Duncan Smith, himself a former soldier, has expressed his party’s “deep misgivings” about undertaking a leading military role in Afghanistan, especially when fighting has not yet ended. In the House of Lords, some peers muttered darkly about the dangers of “overcommitment.” What would happen if a new crisis arose? asked Lord Inge. In the end, when it comes to Britain’s new brand of robust interventionism, idealism inevitably runs up against pragmatism. The spirit may be willing, but what about money and manpower? “It’s all very well for the prime min-ister to say we have the most magnificent troops in the world,” grouses one Army general. “But he has to put his money where his mouth is.” Such sentiments won’t keep Britain from heeding destiny’s call. But don’t expect it to answer with one voice.