Has this ever happened before? Ever?

Can anyone name another instance in which the sitting president and vice-president decided not to show at their party's own convention?

The White House says President Bush and Vice President Dick Cheney will skip the Republican National Convention because of Hurricane Gustav.

First lady Laura Bush still is scheduled to address delegates in St. Paul, Minn., on Monday, the opening day.

Bush spokeswoman Dana Perino says the White House is working on possible alternatives that would allow Bush to make a speech at the convention, which begins Monday.

But Cheney is to leave Tuesday on a four-country trip that includes a stop in Georgia.

Now, Bush is using Gustav as an excuse, and Cheney, as usual, has 'other priorities.' But everyone knows that there's a bigger reason why Bush and Shooter are brushing off the convention: the Republican brand is in tatters, period.

The Google lists no precedent for this. None.

Update: From the look of it, there actually is a precedent. Sort of.

President Roosevelt was making a trip to the South Pacific in order to discuss military strategy with General Douglas MacArthur, and thus didn't attend the convention. This was the last time that a presidential nominee failed to attend a national convention during the 20th century.

No definitive answer on whether Wallace (FDR's VP at the time) or Truman (the Democratic party's choice for Wallace's replacement) showed, but I'm assuming that they did.