Was it viable to continue the battle of France in the French colonies in 1940?

Question

Was continuing the battle of France in the French colonies a viable option in 1940?

This option was advocated by de Gaulle, Churchill, and many leading political figures in France at the time. De Gaulle was specifically tasked by Paul Reynaud to prepare government evacuation and coordinate on the subject with the British.

It is also true that in terms of territory, the losses of the French Empire, after the occupation of France proper, were comparable to those of the USSR when the German army reached Moscow (keeping also in mind that Algeria was not a colony but a department of France).

On the other hand:

• Most of the French industry was located in the occupied zone (unlike the USSR, which had significant industrial capacity east to Moscow, especially in the Urals)
• Colonies couldn't really offer much in terms of military strength, beyond the powerful Mediterranean fleet (this is debatable though - a highly sensitive political subject nowadays is recognition of the Africans who served in de Gaulle's army during the liberation of France)
• Colonies proved to be vulnerable to German allies: to Italy in Africa and to Japan in Indochina.

Answer 1

tl;dr: not really.

Viable to whom?

To you and me? Sure: we know who won in the end, and we risk nothing, having been born long after the war.

To Churchill? Sure: he was committed to fighting to the end, and he would have welcomed any help.

But for a french soldier? No. The year is 1940. Germany seems unbeatable: it was starved into a defeat in WW1 by the naval blockade, but this time Russia is clearly on the German side - a friendly non-combatant if not an outright ally, supplying Germany with food and materiel. Your family is either in the occupied part of France or in the Vichy zone; either way you put them in harms way and you will be branded a traitor, not a hero. When the Germany inevitably wins and you fight for the wrong side, you will never be able to go home.

Besides, fight for what? For Poland? For the Jews? (Hitler always defined his war as "the war on jews").

So, very few people followed de Gaulle.

This attitude was sealed by the Attack on Mers-el-Kébir that

was almost universally condemned in France and resentment festered for years over what was considered a betrayal by their former ally

What was viable?

French Navy was huge and vitally important to both sides. Churchill even offered to release France from the obligation not to make a separate peace (signed in March 1940) in exchange for the ships, or to create a Franco-British Union State.

So, if the French gave their ships to Britain (with or without sailors), that would have been an important development for the anti-nazi alliance (which at that moment consisted of Britain and a bunch of governments in exile in London).

Materiel

Of course, the French colonial industrial resources were virtually non-existent, but that was not the issue: the French would have been supplied by Britain and the US. In fact, the aforementioned Attack on Mers-el-Kébir was intended, in part, to demonstrate to the US that Britain was committed to the war with Germany and that the American aid will never fall into German hands. Thus, if the French navy joined the British (the French overseas ground forces were relatively insignificant - and it is unlikely that many troops agreed to evacuating from Europe to Africa to keep fighting, see above), both "Arsenal of Democracy" and Lend-Lease would have probably came earlier.

The French had the capacity to keep fighting, at least on the high seas, what they lacked was will.

Answer 2

Yes, pursuing fight from French colonies was viable. The "proof" for that is that some of those colonies rallied to French Free Forces and fought other French colonies that were "loyal" to Vichy.

Now, the question is: What would be the consequences?

The problem with continuing the fight has two sides:

First side is that the French metropolitan territory would be under total German occupation, thus the population would be affected differently. How and how much? I won't go into deeper consideration, because there are plenty of debates over that in France. The thing is that this would be a consequence.

What interests us here is the evolution of strategic situation. Here comes the second side of the problem: With France still fighting, the Germans would have had to consider that the fight is not over. Their involvement in Africa, alongside Italy, would have been earlier and stronger. This could be of crucial importance for the Allies.

But French forces in the colonies would have been as well by themselves a consequence: could they compensate more involvement of Germany on Mediterranean and African theaters?

My answer is Yes:

• On the ground, there were plenty of good units able to win over the Italiens and help the British against the Germa,s
• On the sea, French fleet would be a decisive help to kill, and not just contain, the Italian fleet and thus to defend Malta
• In the air, French contribution would have been less important

Thus, speaking of the strategic situation in 1940, continuing the fight from the colonies (with the hypothesis of full commitment and not divisions in French colonies) would have helped in fighting the Axis on the Mediterranean theater, so much that more German involvement might reduce their hability to attack Greece, USSR, and so on. Also, French involvement in the battle of Atlantic should be considered.

In Asia, Indochina would probably not change the course of the war a lot. Only thing: Japan could not invade until Pearl Harbour, and thus the attack of Malaysia and Burma are delayed of a few weeks.