Napoleon took pains over their formation, demanding that the French rather than the Swiss authorities select officers and personnel appointing those above the rank of Major. The 3rd Swiss Demi-Brigade was split, sourcing the personnel for the 1st and 2nd Battalions on 5 July 1805 while in Bastia, Corsica. The 2nd Swiss Demi-Brigade formed the 4th Battalion a month later when it was based in Livorno. The 1st Swiss Demi-Brigade was based in La Rochelle, where it was dissolved on to provide the 3rd Battalion of the new regiment. The men of these remaining small units were merged to form the new 1st Swiss Regiment, formed by imperial decree on 15 March 1805. The remaining three Swiss Demi-brigades, which were the result of the merger of the original six Swiss demi-brigades of the Helvetic Legion. However, it was not until March 1805, just before the Ulm Campaign, that the new French emperor, Napoleon, ordered the reorganisation of the Swiss troops by imperial decree. On 27 November 1803, authorised articles were signed in which a new Swiss infantry regiment was to be created.
