None of the answers so far actually address the question - although they do a nice job of explaining why the AT-ATs were sent in at all.

In almost all other depictions of the Battle of Hoth (various games, and the remastered versions of movie) we see a combined force of AT-ATs, AT-STs, speeders and infantry attacking the rebel lines. Even the original version of the movie included a couple of AT-STs.

So the answer is - the AT-ATs were not sent in alone, but we don't see a lot else in the original movie.

None of the answers so far actually address the question - although they do a nice job of explaining why the AT-ATs were sent in at all.

In almost all other depictions of the Battle of Hoth (various games, and the remastered versions of movie) we see a combined force of AT-ATs, AT-STs, speeders and infantry attacking the rebel lines. Even the original version of the movie included a couple of AT-STs.

So the answer is - the AT-ATs were not sent in alone, but we don't see a lot else in the original movie.