What is the meaning of ‘drive up’?

He was marching up and down in front of the camp when four officers drove up in a car. What is the meaning of ‘drove up’?

In this particular context it's to approach or arrive at a location.

up
adverb

1.So as to approach; near:
came up and kissed me.
American Heritage Dictionary

3To the place where someone is.
‘Dot didn't hear Mrs Parvis come creeping up behind her’
Oxford Living Dictionary

6.to or at a source, origin, center, or the like.
Collins Dictionary

8a : so as to arrive or approach
Merriam-Webster Dictionary

This is a question that's not answered so easily because we use "up" after many verbs. In some cases it changes the meaning entirely, in other cases it doesn't, and removing it would result in much the same meaning.

• I went to the man and asked him for directions.
  

• I went up to the man and asked him for directions.
  

• I drove to Arlington.
  

• I drove up to Arlington.
  

In certain cases there may a semantic difference, but it's only generally known from context. In other cases it may be for emphasis of some sort. For example in "driving to" vs "driving up to" the extra word may possibly emphasize effort or distance (leaving aside the cardinal directions (north/south) or uphill/downhill, or not. It's to be understood in the overall context.

The emphasis can also be on appearing without expectation or quickly, as in this example from Oxford Living Dictionaries:

‘He was talking with his client outside the courtroom when a witness rushed up and attacked his client.’

• it came up behind me
  

is more likely to mean something moved behind you suddenly or without notice more than would be the case from just saying:

• it came behind me
  

It's uses are many and subtle. I doubt I could give a very good explanation of its use and its meaning. However, in the example case you've shown, the meaning is as I explained at the beginning of my answer.