March 3, 2007  -- Talk about a surprise invasion.

Switzerland's army marched into neighboring Liechtenstein this week. But easy-going Liechtenstein seemed to take it in stride.

"It has happened before," Liechtenstein government spokeswoman Gerlinde Manz-Christ told ABC News. "Nobody really realized it."

Early Thursday, 170 Swiss soldiers on a training mission got lost in the rain and wandered over the unmarked border. They were a mile into Liechtenstein before they realized their mistake.

Swiss authorities informed Liechtenstein their border had been breached and the commanding officer gave an official apology.

The principality of Liechtenstein is slightly smaller than Washington, D.C., and has no standing army, but does not seem worried.

"Who could cross the border except for the Swiss?" Manz-Christ said. "We are surrounded by neutral countries, so that leaves us in a comfortable position."

Prosperous Little Liechtenstein

It is indeed hard to disturb the peace in such a content country. Liechtenstein boasts more than 200 years as a sovereign state with consistent borders.

The population is healthy and wealthy, and the capital, Vaduz, boasts a startling number of five-star restaurants.

While much of Europe struggles with high unemployment, Lichtenstein has more jobs than it can fill with its 35,000 inhabitants.

And the nation brings a smile to much of the world, literally. Manz-Christ says one third of the world's false teeth are manufactured in Liechtenstein.