Final answer:
The French were able to arrive at the Battle of the Marne in time due to the transfer of troops, the assistance of the British forces, and the successful resistance against the German offensive.
Step-by-step explanation:
The French were able to arrive at the Battle of the Marne in time due to several factors. Firstly, the French troops were transferred from the southern border with Germany to mount a fierce resistance. Secondly, the British also rushed to Northern France to join the French in their defense against the German offensive. Lastly, the French troops successfully stalled the German offensive at the Battle of the Marne and forced the Germans to retreat.