As it was played by Josef Marais and Miranda, it was a simple song, as marching osngs often are:

We are marching to Pretoria, Pretoria, Pretoria
We are marching to Pretoria
Pretoria, Hooorah!

You sing with me, I'll sing with you and so we will sing together
So we will sing together
So we will sing together
Sing with me, I'll sing with you and so we will sing together
As we march along.

We are marching to Pretoria, Pretoria....etc.

Repeat with other verbs in place of "sing" such as talk, march. As a youth I used to spice it up by adding a "sleep" verse, but it didn't make a hit.

A