The national flag of Switzerland[a] displays a white Greek cross in the center of a square red field.

[3] The white cross has been used as the field sign (attached to the clothing of combatants and to the cantonal war flags in the form of strips of linen) of the Old Swiss Confederacy since its formation in the late 13th or early 14th century.

[4] As a national ensign, it was first used during the Napoleonic Wars by general Niklaus Franz von Bachmann, and as regimental flag of all cantonal troops from 1841.

The federal coat of arms (eidgenössisches Wappen) was defined in 1815 for the Restored Confederacy as the white-on-red Swiss cross in a heraldic shield.

[5] The civil and state ensign of Switzerland, used by Swiss ships, boats and non-governmental bodies, is rectangular in shape and has the more common proportions of 2:3.

Since then, the colour of the flag is defined as pure red, with the color values as follows: The ultimate origin of the white cross is attributed by three competing legends: to the Theban Legion, to the Reichssturmfahne (Imperial War Banner) attested from the 12th century, and to the Arma Christi that were especially venerated in the three forest cantons, and which they were allegedly allowed to display on the formerly uniformly red battle flag from 1289 by King Rudolph I of Habsburg at the occasion of a campaign to Besançon.

The Lucerne chronicle of 1513, in battle scenes of the Burgundy wars of the 1470s shows cantonal flags with an added white cross.

Other depictions in the illustrated chronicles show a flag of Schwyz with an asymmetrical white cross, drawn in greater detail.

The first explicit mention of a separate flag representing the Confederacy dates to 1540, in the context of an auxiliary force sent by the Swiss to aid their associate, the city of Rottweil, in a feud against the lords of Landenberg.

Beginning in the later 16th century, forces of the individual cantons adopted a type of flag which was based on a white cross design.

These flags usually showed a white cross drawn to the edge of the field in front of a background striped in the respective cantonal colours.

After the French invasion of Swiss territory in 1798 and the subsequent collapse of the Confederation, the authorities of the newly proclaimed Helvetic Republic confiscated all earlier flags, replacing them with a green-red-yellow tricolour.

The term Schweizer-Fahne (later spelling Schweizerfahne) is in use for the flag from this time, recorded in a poem on the Battle of Näfels by one J. Hottinger published in 1808.

The commission for drafting a federal constitution on 16 May 1814 recommended the adoption of a seal of the Confederacy based on the "field sign of the old Swiss".

However, the white cross in a red field had seen frequent use on flags flown by private organizations during the Regeneration period (1830s), especially shooting, singing and gymnastics associations which at the time were a pool for progressive or "radical" agitation.

[18] Seals produced from 1815 onward, and cantonal coins minted from 1826 showed the arms of the cross in the 7:6 length to width ratio.

The 1889 law explicitly avoids specification of the shape of the shield, which was to be left to the "tastes of the current time and practical necessity".

Destruction, removal or desecration of a Swiss, cantonal or municipal flag or coat of arms that has been installed by a public authority is punishable by a monetary penalty or imprisonment of up to three years according to the federal penal code.

Use of the Swiss flag is generally permitted with the provision that such use "is neither misleading nor contrary to public policy, morality or applicable law".