Belgium under Leopold III had a very self-destructive foreign and military policy, in my opinion. One of the least explored, but most potent PODs for World War II is delaying Leopold's succession. (His predecessor died in a quite avoidable accident and could easily have lived well into World War II).
Leopold did an awful lot of things wrong, including the dumb defensive deployments. Two of the worst things he did though, were:
(1) Ordering Belgian forces out of Belgian portion of the Ardennes when the German attack started. Worse than that: they blew bridges and created obstacles, but didn't try to do any kind of rear-guard defenses behind them. The demolitions delayed the French coming in to defend the Ardennes more than they did the Germans. The impact of the Belgian withdrawal was huge. In one case where German bombing destroyed communications and a trivial-sized (one company I think) Belgian force didn't get the order to withdraw, they held up an entire Panzer division for around a day at one of the choke-points. The French were counting on it taking the Germans around ten days to fight their way across the Ardennes. But that assumed Belgian resistance, which for the most part didn't happen.
If it had taken the Germans even six days to get to the Meuse river instead of three, the battle for France would have had a very different complexion. Give the French time to stabilize their line in Belgium, get Ninth Army set up along the Meuse River, and give the French time to start getting the mobile units that had screened the infantry advance into Belgium back into reserve, and I don't know if the Germans win. It certainly leads to a much more hard-fought battle.
(2) Surrendering Belgian forces while giving the French and British very little notice. That turned a very bad military situation into a hopeless one. If you look at the battle lines before and after Belgian surrender it is pretty obvious that the surrender cost the Allies dearly--left them in a militarily hopeless situation and lucky to get anybody out.
Leopold did an awful lot of things wrong, including the dumb defensive deployments. Two of the worst things he did though, were:
(1) Ordering Belgian forces out of Belgian portion of the Ardennes when the German attack started. Worse than that: they blew bridges and created obstacles, but didn't try to do any kind of rear-guard defenses behind them. The demolitions delayed the French coming in to defend the Ardennes more than they did the Germans. The impact of the Belgian withdrawal was huge. In one case where German bombing destroyed communications and a trivial-sized (one company I think) Belgian force didn't get the order to withdraw, they held up an entire Panzer division for around a day at one of the choke-points. The French were counting on it taking the Germans around ten days to fight their way across the Ardennes. But that assumed Belgian resistance, which for the most part didn't happen.
If it had taken the Germans even six days to get to the Meuse river instead of three, the battle for France would have had a very different complexion. Give the French time to stabilize their line in Belgium, get Ninth Army set up along the Meuse River, and give the French time to start getting the mobile units that had screened the infantry advance into Belgium back into reserve, and I don't know if the Germans win. It certainly leads to a much more hard-fought battle.
(2) Surrendering Belgian forces while giving the French and British very little notice. That turned a very bad military situation into a hopeless one. If you look at the battle lines before and after Belgian surrender it is pretty obvious that the surrender cost the Allies dearly--left them in a militarily hopeless situation and lucky to get anybody out.