Charade

My first like my second, not easily tamed
Would vex the best monarch in history famed
My second a monarch himself in the field
To force far inferior is oft forced to yield.
But my whole were a monster in Britain if shown
Where a free constitution makes harmless the throne
Where my second the emblem of all that is great,
Will shield from destruction of Europe the fate.

To be answered by the Society in a couplet ending

 ----------- breast
 ----------- expressed.