The French support of the colonials during the American Revolution was essential to their ultimate success in defeating the British troops and securing their future as an independent nation. The cause of the American patriots was not seeing much success against the British for a good long while after the start of the war. This was caused, mainly, but the lack of trained troops, which the British had abundantly, and the British naval fleets and arms.
On the other hand, the colonists had to recruit minutemen and establish militias in hopes of being able to defeat the British. One of the only hopes of the colonists was to seek support from the French government and military, who could then back them financially, and in terms of supplies and men, thus securing them a victory. The bad blood between the French and the English went back a long time.
These two powerful countries were always in conflict and even from the beginning of the rush to claim land in the New World, they were in competition, each claiming parts of the lands that would now be Canada and the United States of America. When the French saw an opportunity to get back at the British and help defeat them, thus effectively kicking them out of the New World, they took it. They especially did so because they were impressed with Benjamin Franklin, who spent a great deal of time in Paris trying to drum up support for the colonists and their cause.
The French saw the benefit of finally defeating their greatest enemy, and eliminating them from any future developments in America. The war would not have been won by the colonists if it were not for the French. The French provided financial backing, arms, supplies, and troops to help their efforts, and the French were essential to the victory of the Continental Army at Yorktown. Without France, the outcome of the Revolutionary War would have been very different, changing the course of history forever.