Two hundred years ago this week, the British Parliament outlawed the slave trade throughout the British Empire.

This hard-fought battle is beautifully told in the new film Amazing Grace. I watched a preview with President Bush at the White House this week, which was appropriate, seeing that this president has successfully fought against slavery in Sudan and against sexual trafficking. The movie, which opens this Friday, is sensational. See it, be inspired, and you will learn one of the most important lessons of politics: If you hope to overthrow a great social evil...one to which people have become accustomed...it's crucial that you take the incremental approach.

It's a strategy the Great Abolitionist learned early on. When Wilberforce began his battle in 1787, slavery was both accepted and highly profitable. The slaves lived and died in the Caribbean, far from English eyes.

William Pitt, then prime minister and Wilberforce's friend, introduced a resolution in Parliament to discuss the slave trade. The motion passed easily. After all, the slave industry was not worried about a motion just to discuss abolition.

The next move was to introduce a one-year experimental bill regulating the number of slaves that could be transported per ship.

Wilberforce then gave his colleagues a first-hand look at the slave trade. As depicted in the film, he took several MPs to view a slave ship docked in London. They were horrified by the odor of death.

The slavers woke up then to their danger...and put their money to work. In 1789, despite impassioned speeches by abolitionist leaders, the slave industry prevailed against Wilberforce.

So Wilberforce took his campaign to the public. He and his followers spoke at meetings, wrote songs, and organized a boycott of slave-grown sugar. The tide began to turn...but once again, the slave industry exercised its political muscle.

In 1792, Wilberforce made a motion to abolish the slave trade. In response, the House of Commons demanded that one word be added to the bill: the word gradually. The slavers knew the great value of that seemingly innocuous adverb.

Wilberforce was crushed. Yet, he knew this was a partial victory. For the first time, the House had actually voted for an abolition motion.

Over the next few years, victory often seemed within grasp. But year after year, anti-slavery motions were thwarted and sabotaged. An exhausted Wilberforce almost gave up.

But by 1804, public sentiment for abolition was growing. In 1805, England had a new prime minister, William Grenville, a staunch abolitionist who was willing to try new tactics.

And in February of 1807...twenty years after the battle was joined...Parliament outlawed the trafficking of humans.

The pro-life lobby has learned the Wilberforce lesson. Instead of demanding an immediate end to abortion...an impossible goal...they have passed informed-consent laws and taken on partial-birth abortion. They have spent decades educating the public.

The result: Young people today are significantly more pro-life than their parents.

See Amazing Grace: It will deeply inspire you and teach you how to fight...and win...battles against today's social evils