GAINING AND LOSING UNITS
OCCUPYING SUPPLY CENTERS. Occupation of a supply center by a Great Power occurs when one of its units is located in that supply center immediately after a Fall move, complete with retreats, if any, has been played. Once occupation has been established, the center may be left vacant as long as the player sees fit, and it will still suplly one of his units, unless another Great Power establishes occupation of it.
After the Fall moves have been played, and the retreats, if any, made, each player's number of units is adjusted to equal the number of supply centers his country controls. If he has to remove units, he chooses which ones to remove. If he gains units, he mya place them, one in each unoccupied supply center in his home country only. (provided such supply centers are still under his control.) He must specify a fleet on an army in a coastal supply center. (If Russia builds a fleet in St. Petersburg, Russia must specify on which coast it is to appear.) If his home supply centers are all occupied by his own units or under foreign domination, a player must wait until the next Fall move on which this situation can be corrected to raise any unit to which he may be entitled; though by occupation of supply centers he may reduce the forces of some other country. (From this it should be clear that if he has lost all his home supply centers, he may still fight on with the units and supply cneters remaining under his control, but he may not gain units untill he recaptures a home supply center and leaves it vacant at the close of a Fall move.