David Cameron got his way but saw his party torn in half as gay marriage legislation cleared its first hurdle in the Commons.
The Prime Minister hailed a "step forward for our country" after the House backed the proposals by a big margin of 400 to 175.
However, Labour and Liberal Democrat support masked a massive show of protest by Tories, with 136 taking advantage of a free vote to register opposition. Just 127 endorsed the proposals at second reading, with 40 more either formally abstaining or not voting.
Environment Secretary Owen Paterson and Welsh Secretary David Jones voted against, while fellow Cabinet minister Philip Hammond, the Defence Secretary, and Attorney General Dominic Grieve stayed away.
However, Downing Street will be heaving a sigh a relief after no Government members quit to join a rebellion over the timetabling of the legislation, which involved a whipped vote. Attention will now turn to the Lords, where opponents of the plans are expected to mount tough resistance.
Responding to the result on Twitter, Mr Cameron wrote: "Strong views exist on both sides but I believe MPs voting for gay people being able to marry too, is a step forward for our country." Labour leader Ed Miliband - who saw 22 of his own MPs rebel against the legislation - said it was a "proud day".
Deputy Prime Minister Nick Clegg said it was a "landmark for equality". He said: "Tonight's vote shows Parliament is very strongly in favour of equal marriage. Marriage is about love and commitment, and it should no longer be denied to people just because they are gay."
The result followed more than six hours of stormy debate on the Marriage (Same Sex Couples) Bill. Culture Secretary Maria Miller said the legislation would make England and Wales "a fairer place to live", and insisted religious organisations which did not want to conduct gay marriages had protection.
But Tory MPs lined up to condemn the measures - including the chairman of the backbench 1922 Committee Graham Brady, who said he had "serious misgivings" over assurances on religious freedom. Former defence minister Sir Gerald Howarth said that the Government had no mandate for such a "massive social and cultural change".
Four of the 56 Liberal Democrats opposed the legislation at second reading - including former coalition minister Sarah Teather. In a statement, Ms Teather said she was concerned that the definition of marriage was being changed, and that could make family life more unstable.
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