That is mixing up quite a few different things. World Calendar [1] was proposed in League of Nations/United Nations, but it was created by US person. There was

That is mixing up quite a few different things. World Calendar [1] was proposed in League of Nations/United Nations, but it was created by US person. There was slightly earlier proposal, International Fixed Calendar[2] from British person that also had some popularity. Neither of these were decimal calendars though, that is something from French revolution [3], and even they did not really manage to make it very decimal. Afaik the most vocal opposition to reforms came from the US [1] https://en.wikipedia.org/wiki/World_Calendar https://en.wikipedia.org/wiki/World_Calendar [2] https://en.wikipedia.org/wiki/International_Fixed_Calendar https://en.wikipedia.org/wiki/International_Fixed_Calendar [3] https://en.wikipedia.org/wiki/French_Republican_calendar https://en.wikipedia.org/wiki/French_Republican_calendar