The ballot amendment that aimed to change the California Constitution came about after a landmark decision by the state’s Supreme Court.

On May 15th the court ruled that the statute enacted by Proposition 22 in 2000 and other statutes that limit marriage to a relationship between a man and a woman violated the equal protection clause of the California Constitution.

The Court voted 4 to 3 to strike the ban on gay marriage in California, making the state only the second in the US after Massachusetts to allow same-sex couples to marry legally under state law.

Gay and lesbian couples had the right to get married in the most populous state in the union. Conservative reaction was swift.

By June 2nd Proposition 8 had qualified for the election day ballot with 1.12 million signatures, hundreds of thousands more than the minimum required to trigger the statewide referendum.

It sought to add a new clause to the constitution: “Only marriage between a man and a woman is valid or recognised in California.”

On June 17th, same-sex marriages began. It is estimated that more than 18,000 couples have married since then.

Campaigning began in earnest on both sides, and in excess of $50m (£31.2m) would be raised in the coming months.

On July 22nd the California Secretary of State changed the official title of Proposition 8 to reflect the fact that same-sex couples were already getting legally married to:

“Changes the California Constitution to eliminate the right of same-sex couples to marry in California.”

The summary still says Proposition 8 provides that “only marriage between a man a woman is valid or recognised in California.”

In June the Mormon church entered the fray, calling on its members to join the effort to amend the state’s constitution.

Roman Catholic bishops donated $100,000 to the Prop 8 campaign. In August Mormons, Jews, Sikhs and Hindus were asked to join forces to support the amendment.

Supporting gay people were the celebrities.

Not just gay and lesbian stars such as Ellen Degeneres, Melissa Ethelridge and George Takei, who took advantage of the court ruling and got married, but straight allies too.

Steven Spielberg and Brad Pitt both donated $100,000 to the campaign to defeat Prop 8.

Google also put its money behind gay marriage, while Apple said it was a human rights issue and came out in opposition to Prop 8.

Ugly Betty stars America Ferrara, Tony Plana and Ana Ortiz appeared on Spanish language TV stations in an advert for No on Prop 8 and spoke up for gay rights.

This month California’s First Lady, Maria Shriver, a niece of former President John F Kennedy, said: I believe in people’s right to choose a partner that they love, and that’s a decision that I have come to, and I have felt that way for a long time.”

Days later her husband, action star and Governor of California Arnold Schwarzenegger announced he would be voting against Prop 8.

The Screen Actors Guild voted to officially oppose the California ballot initiative.

In the final weekend of campaigning, with the most recent Field Poll showing 49% of likely voters oppose Proposition 8 and 44% support it, with 7% undecided, things got heated.

Brad Dacus of the conservative Pacific Justice Institute stood on the steps of the state Capitol in Sacramento and compared gay marriage to “Nazi Germany with Adolf Hitler.”

Some light relief was provided by comedian Sacha Baron Cohen, who took his camp Austrian character Bruno on to the streets of LA to take part in a pro Prop 8 rally. He was quickly rumbled.

Connecticut just legalised gay marriage.

New York and other progressive states are expected to follow California and Massachusetts and grant full marriage rights to all citizens.

Prop 8 was the biggest battle for gay equality in the US so far, but it is unlikely to be the last.