Thanks for your interest.

The song is sung from the viewpoint of a ghost ('we left it buried in the bloody fields of France') reflecting that the 'war to end wars' did not end wars at all. Hence the reference to the Maginot line ('beyond the lines of Maginot'). More a reference to time than to space.

The idea is that the 'grand illusion' of the song has been left buried beyond the lines of Maginot.

The main point of the lyric at this point was to stress that, against all hope and idealism, there was a Second World War.

Rather than an oversight, the reference to the Maginot line was highly conscious.

I hope that's helpful.

Thank you for your interest.

Best wishes.

P.S. Glad to see my song still has a life of its own.
.