aDJUsTing nUMbeR Of UniTs
After each Fall turn (including retreats, if any), players adjust their units to match the number of supply centers they control. This may result in some units being disbanded (if the player has lost supply centers that year) or in some units being built (if the player has gained supply centers that year).
As with retreats, gaining and losing units (collectively known as “adjustments”) are written and revealed simultaneously
without discussion or diplomacy of any kind.
Retreats.
After all the orders have been revealed and read, the moves made, and the conflicts resolved, any dislodged (defeated) units make their retreat. These retreats are written down (just like orders) and revealed immediately. No diplomacy or discussion takes place prior to writing retreat orders—all countries are on their own.
https://media.wizards.com/2015/downl...macy_rules.pdf
Page 18.