Are we allowed to add counter strategies to this thread? I would as Germany focus on armored pushes into Denmark, coordinated with large-scale bombing runs on factories and units, make sure to have naval support when possible, and make sure that all infantry divisions in the offensive are specialized marine templates with recon, engineer, and signal companies.
France
Industry/Technology
As France, 1st day is focus on civilian and military factories in all regions, researching concentrated industry (if you are having industry problems with bombing, you have survived pretty long), encryption technology to hide our forces and discover theirs, fighter techs and doctrines for preventing bombing runs if possible, artillery and infantry weapons to improve firepower, and Grand Battle Plan doctrines to improve planning bonuses and entrenchment. Priorities are industry and Grand Battle Plan doctrines, so there should always be research in these trees going until the end of the game. Secondary priorities are encryption and fighter doctrines to improve performance of our forces. Infantry weapons and artillery techs will be situational so if German victory is expected within say 60 days, there is no point in researching better weapons just to scuttle the efficiency bonuses for factories.
Naval
There will be no focus on naval ships. Naval doctrines will be researched if there is no relevant research (industry, encryption, land doctrine, infantry/artillery, fighter tech). Naval capacity will be used on the biggest ship(s) that can be finished before August 1939. The navy will focus on trading evenly or better with the German navy. If the UK player is human, the French navy can coordinate with the UK fleets for better return on investment.
Airforce
There will be no bomber production. Existing bombers will be assigned to destroy infrastructure/divisions in German provinces near Luxembourg. All plane production will be for fighters only, with fighters assigned to Northern France mainly. Fighter doctrines and techs will be researched on a opportunistic basis but with a higher priority than the naval techs.
Army
The focus will be on strong, resilient Northern France infantry equipped with recon to counter German tactics, mountaineers for rough terrain, and engineer companies for faster entrenchment. Lower-grade infantry used for the Spanish and Italian borders will only have mountaineers. If Germany focuses on tank production, anti-tank brigades will be added to the Northern France templates. If it is infantry-focused, all production will be for combat artillery. Combat artillery will be added if there is enough factory capacity to equip the Northern France region. In general, if there is not enough infantry equipment production, other more specialized equipments will be neglected until there is enough infantry equipment. Every French soldier must have his rifle, ammunition, a shovel, and grenades. This is a critical priority.
Border Plans
The military plans are based on expecting German victory in 1940. Any delay in the German offensive is considered to be desirable by French high command. Defensive ministers will be used to improve defense, infantry performance, and air superiority efforts. Lower-end troops will be stationed on Italian borders and only garrison troops on the Spanish border if it is Nationalist Spain but not preparing for war. If it is Republican Spain, it could be worth just leaving the entire border empty. If it is Nationalist Spain and preparing for war, the border will receive enough lower-end troops roughly equal to the Italian border.
There will be one primary defense commander for the provinces bordering Germany and Luxembourg, with only infantry divisions. All armored/motorized divisions will be under a mobile tank commander responsible for plugging holes in the front-line. The Italian and Spanish borders will receive second-tier commanders to hold as long as possible. Possibly a second defense commander will be used to prepare troops on the Belgium line.
Combat Tactics
French generals will be looking for even lines of defense. If certain provinces in the front-line are mountains or forests and others are plains, there should either be fortifications on the plains to provide a consistent line of defense or more likely a fallback position that uses rivers and forests to maintain a line. In the latter case, front-line divisions will only hold the initial provinces long enough for backup forces to form up at the secondary defense line. Fighting retreats are expected in North France. Strategic space will only be traded for better defended positions, so once these positions are reached, all efforts will be made to hold them. If western German defenses seem especially weak during their invasion of Poland, opportunistic attacks will be made. If Belgium joins the Allies early, the second defense commander will be directed to move into Belgium cities and forests.
If troop reinforcements from Spanish and Italian borders are possible, they will be diverted to the German defense line. If UK army reinforcements arrive, French defense lines will re-assign based on UK defensive positions. If the UK is player-controlled, French commanders will communicate shared attack goals, operation timing, and risk assessments.
Operation Length
If France holds most critical provinces for 3 months after the primary German offensive, this will be considered an acceptable outcome. Six months will be considered to be strategic victory as the German war machine will be ground down by Allied air attacks and face an existential threat in a modernizing Soviet Union.
If the Soviets invade Germany and French defense still holds strong, a broad military reassessment will be made to prepare for an expected French/British war against Soviet forces in 1948. Finally, secret diplomatic cables with Germany will encourage them to surrender as much territory to French/British forces instead of the Soviets. As fellow Western Europeans, we will guarantee fair treatment of all German forces and people, and investment in re-building Germany under a more fair and humanitarian government.