You do not ever throw all of your troops into the first attack. You always must have a reserve ready to counter the enemy breakthrough.

Listen to your own arguments. On the one hand you claim they could not possibly spare any troops for a reserve force, and on the other claim that Gamelin was "extremely bold & reckless". You can't have it both ways: if he was conservative he would have held some of his best units that were to surge into Belgium in reserve to counter the German attack.

You do not ever throw all of your troops into the first attack. You always must have a reserve ready to counter the enemy breakthrough. Listen to your own arguments. On the one hand you claim they could not possibly spare any troops for a reserve force, and on the other claim that Gamelin was "extremely bold & reckless". You can't have it both ways: if he was conservative he would have held some of his best units that were to surge into Belgium in reserve to counter the German attack.

The allies could not afford NOT to be bold, because letting the Germans bring the fight to France northern territories would wreck the country's industry and war production capabilities.

They couldn't wait "to surge when needed" because of economical and diplomatical pressure, doing so would drive the much needed Belgian & Dutch manpower away, expose the French industrial heart, ruin morale by making the leadership look weak and forsake the initiative for the whole campaign.