The calendar we use today is basically the Julian calendar - introduced in 45 BC by Julius Caesar. In 1582 Pope Gregory XIII made only a minor amendment to this calendar concerning leap years in order to prevent the calendar from lagging behind the solar year by 1 day in every 128 years - minimising this error to 1 day in every 3322 years.
The division of the calendar into weeks increased the number of versions from two to fourteen, and the introduction of a moveable Easter meant that since 325 AD we have been using a calendar in as many as 490 versions - each year the calendar brings us a different arrangement of weeks and holidays, a different number of working and non-working days. A new field was developed - standardisation - which includes, among other things, unification, that is reducing issues to a single form or standard.
In 1834, Marco Mastrofini (1763-1845), an Italian priest, philosopher and mathematician, proposed the unification of the calendar and the introduction of a fixed calendar. Half a century later, the French Astronomical Society organised a special competition to create a new, fixed calendar.
Enthusiasts of reforming the calendar managed to get the International Congress of Chambers of Commerce to pass a resolution in support of the reform, while the Swiss government pledged to take appropriate diplomatic action.