The Southampton Plot of 1415 was an attempt to overthrow the Lancastrian King Henry V and replace him with the Yorkist Edmund Mortimer, Earl of March, regarded by some as the lawful heir of Richard II. The ringleader of the conspirators was Richard, Earl of Cambridge, a landless and disaffected peer and heir apparent to his elder brother, Edward, Duke of York. Cambridge was aided and abetted by Sir Thomas Gray of Heton and Henry, Lord Scrope of Masham, one of the king’s councillors. The conspiracy was uncovered in Southampton, as the king and his army were preparing to invade France on a campaign that was to culminate in the Battle of Agincourt in October 1415.
It was Edmund Mortimer, the intended beneficiary of the plot, who betrayed the conspirators, quickly realizing that it had no chance of success. The three conspirators were arrested at Portchester Castle on the 31 July and tried at Southampton Castle (claims that the trial took place in the Red Lion public house on the High Street are almost certainly untrue). The conspirators were convicted of plotting to kill the king and his three brothers, which, if successful, would have ended the male line of the Lancastrian dynasty. Sir Thomas Gray was executed on the 2 August, and Cambridge and Scrope were beheaded outside the Bargate on the 5 August. Richard, Earl of Cambridge was buried at God’s House chapel (now the French Church) and is commemorated by a stone tablet erected in 1766.

Further reading:
History of Southampton, by Rev. J. S. Davies, p469-470. (HS/h)
Southampton Occasional Notes 2nd Series, by ‘Townsman’, p18. (HS/h)
Henry V and the Southampton Plot of 1415, by T. B. Pugh. (HS/h)


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