What is the meaning of the phrase “can’t go on”?

I quarreled with my brother

I don’t know what about,

One thing led to another

And somehow we fell out.

The start of it was slight,

The end of it was strong,

He said he was right,

I knew he was wrong!

Eleanor Farjeon is the author of this excerpt from "The Quarrel".

What does the underlined phrase mean in this stanza?

Just as he trumpeted, he heard a loud crashing and stamping. A herd of wrinkled elephants came charging up.

What is the meaning of the word "charging up’’ in the above sentence?