Defenders will drop extra men from their seemingly impregnable rush defence lines.

But with enormous courage they toppled three seemingly impregnable dictators.

Masterly cross-examinations and brilliant closing speeches that destroyed a seemingly impregnable prosecution would be meticulously reconstructed on the page.

Even in the long term, a seemingly impregnable wall of corporate indifference to what we were trying to achieve did not deter us.

The castle was surrounded by a triple ring of forts making its position seemingly impregnable.