The Nixon campaign spotted the problems and disruption amongst Democratic supporters and sought to exploit these and tap into previously unreachable votes. Nixon began his 1968 campaign on the message of "state rights" and "law and order" and it proved popular; he picked up Virginia, Tennessee, North Carolina, South Carolina, and Florida. Whilst Humphrey, the Democratic candidate, managed to hold Texas, the other Southern states were won by an independent candidate, George Wallace, who did somewhat negate Nixon's Southern Strategy by being almost explicitly opposed to integration and black civil rights.
The Southern Strategy proved an effective tool in the Republican campaign arsenal in the 1968 election; it was to be even more influential in the 1972 presidential campaign, as the same fears and resentments began to spread among the white working class around the country. Nixon managed to win every state except Massachusetts, taking over 70% of the popular vote in the Southern states, with an overall percentage of 61% of the national vote.
Even though he appealed strongly to white Southerners, Richard Nixon portrayed himself as a moderate, not an anti-Civiil Rights candidate, which allowed him to maintain the Republican wins in other states. He gained a cemented majority in the electoral college because he was able to appear reasonable to many Americans. The Southern Strategy talked about integration and Civil Rights subtly through "states' rights"and "law and order," amongst other smaller issues that were relevant for voters in the South.
So what do we have today? The Republican Party faces an election that could very well leave them as an irrelevant and regional caucus party. In the last election, President Obama won two traditional Southern states (it would be three if you consider Florida to be Southern and/or traditional): North Carolina and Virginia. No Democrat had won Virginia since 1964. Obama's 2008 victory in North Carolina was a watershed moment, in which he won a decisive 364 electoral votes. No Democratic president had won the Tar Heel State since 1976.
With a solid blue map from Vermont down to Maryland and Oregon down to California, a traditional hold on the Midwest rust belt, and more states turning blue in the Southwest, the GOP cannot afford to cede ANY Southern states and have a chance of winning.
So now we have the 2012 version of the Southern Strategy--a desperate gamble to lower the African-American vote in key Southern states by creating a wedge between blacks and gays--a divide and conquer strategy.
There are numerous reports that there are national efforts underway to use the issue of gay marriage--which remains controversial among many African-Americans in general, and religious blacks in particular--as a way to deny President Obama a win in the key battleground states of North Carolina, Virginia, and Florida.
The ultimate goal is to convince just enough African-American voters in these key states that by voting for President Obama, they will be voting to make same-sex marriage legal. Republicans don't expect these voters to vote for Mitt Romney instead, but if enough stay home, they can retain 28 electoral votes and possibly win the White House.