Very revealing article from the "newspaper of record", select quotes:

how each side was funded pretty equally

In 2004, when 13 states approved constitutional amendments against same-sex marriage, $6.8 million went to support their passage and $6.6 million against, according to an analysis by the National Institute for Money in Politics. In 2008, when three more states adopted constitutional bans, $49.8 million was spent in favor and $50.8 million against.

turn the tide, attack people personally

It was that year Mr. Karger decided to make famous every significant donor to the $40.5 million effort to pass Proposition 8. His group, Californians Against Hate, mined disclosure reports and listed everyone who contributed $5,000 or more to pro-Prop 8 committees on a “dishonor roll” website, with phone numbers and business addresses. Other activists made the data searchable via Google Maps, and he pitched out-of-state newspapers to cover local megadonors to the pro-Prop 8 group Protect Marriage.

ruin people's businesses

But Mr. Manchester did not remain sanguine for long. The next year, he dispatched an aide to an International Gay and Lesbian Travel Association conference with an offer: $25,000 in cash and $100,000 in hotel credits for dropping the boycott. No one appeared to accept the deal, and Mr. Karger kept up the pressure on the hotels, persuading business groups to yank conferences. In late 2010, Mr. Manchester was forced to sell the property.

they see that it works

“The impact of donors being scared off was significant,” said the National Organization for Marriage’s chief strategist, Frank Schubert. “The first thing they wanted to know is, ‘Am I going to be publicly disclosed?’”

they win the spending war

Overall, more than two-thirds of the money spent on ballot referendums in 2012 went to advance same-sex marriage. Only in Minnesota was there anything approaching parity between the sides. In Washington State, where Amazon’s founder, Jeff Bezos, and his wife gave $2.5 million to a campaign to pass Referendum 74, which would legalize same-sex marriage in the state, proponents outspent opponents more than five to one.