What's the grammar behind "A'warring", from the lyrics of Symphony of Destruction?

apostrophe

What's the grammar behind A'warring, from the lyrics of Symphony of Destruction by Megadeth?

It's the first time I'm seeing the use of such apostrophe.


The a- prefix to gerunds or participles of verbs (of motion, in particular), often as an intensifier, is rather old-fashioned or archaic in British English, but still common in certain regional US dialects. An apostrophe can be used in place of a dash.

A-prefixing

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