The combined arms rule (actually called “Commander In Chief”) was in the first edition of Classic but was removed from the second edition of Classic. Apparently they thought back then that this rule was to easily taken advantage of by Allied players.
The way it worked was:
The US moves “X” units to United Kingdom. The UK already has a number of units already there. The US moves a number of transports that can carry all the current US and UK units on United Kingdom to the sea zone adjacent to the territory.
During the Collect Income phase of the US turn, the US and UK players agree to make the US Commander In Chief. The US player takes a stack of 3 US control markers and places them in United Kingdom.
Then on the UK player’s turn, the UK player does not move any of the units intended for the combined force. If the UK moves any of it’s units stationed on United Kingdom, they CAN NOT be included in the combined force.
Then on the US player’s next turn, the US player is now free to move any or all units stationed on United Kingdom as long as they DID NOT move during the UK player’s turn.
By the way, this includes UK aircraft if they didn’t move on the UK’s turn.
So, basically, any country’s units that are going to be included in the combined force but are not from the country of the Commander In Chief have to be in the launching territory before the Commanding player is chosen. It might be a little more complex, but I think this rule could be applied to Global 1940.
For example: Say England wants to attack a Japanese force in Burma from India. They want to use a combined force of UK, US, Soviet and ANZAC units. So on UK Pacific’s turn, UK can move units into India. On the UK’s Collect Income phase, they get chosen as Commander In Chief. The Soviet, US and ANZAC forces have to be already in India at this time and those are the ONLY non UK forces that the UK can move next turn. Even if one of the other countries move more units into India, those new units could NOT be used in the UK’s next turn.
Assuming the UK attacks Burma with the combined force and defeats the Japanese, UK India will get possession of that territory. Also, I believe the last casualty HAS to belong to the Commander In Chief’s country (in this case, UK).
