The LON was weak (having proven to be ineffective in solving disputes)and so was Britain's army, therefore this would not have been enough to intimidate Hitler into backing down. The people of Britain and France would also be very unhappy had their government dare to oppose Hitler (which would increase to possibility of a war)

(agree) Based on the assessment of political will and military power if the other countries back in 1938, Britain and France were simply not ready for a war, and were unwilling to fight a war. Britain's army was too small and too weak. Moreover Great Britain was a democratic country, Chamberlain was not a dictator with the right to start a war if he pleased. He could not go to war without the support of the people – and until 1939 most people wanted peace, almost at any price.