Once Switzerland had been drawn into the French sphere of influence, it could not escape the war that raged through Europe for the next 16 years. In 1799 it was an unwilling battleground as Austrian and Russian troops tried unsuccessfully to dislodge the French. The presence of large numbers of foreign troops further impoverished the country.

The Helvetic Republic soon proved unworkable, as the parliament was torn between federalists and centralists. The country slid into civil war, causing Napoleon to intervene as "Mediator of the Helvetic Republic."

In March 1803 he passed the Act of Mediation, which left very little of the centralised republic in place. It restored the old cantonal system, though it elevated the former subject territories to cantonal status.

As a result, six new cantons were created - the first change in Confederation membership since 1513. They were Aargau, Graubünden, St Gallen, Thurgau, Ticino and Vaud.

The new constitution implicitly recognised Swiss neutrality, but the Swiss were still obliged to supply troops for the French army. This was a very unpopular measure. Although the number to be supplied was gradually cut from 18,000 to 12,000, many Swiss died fighting for France.

Their best known exploit was the battle they put up at the river Berezina during Napoleon's retreat from Moscow after his ill-fated Russian campaign of 1812. For a whole day, some 1300 Swiss troops kept off 40,000 Russians while the rest of the army (or what remained of it) crossed the river on pontoons. The cost in Swiss lives was enormous: only about 300 survived, but the French had been saved from complete destruction.