Anthony Ascham and his interpreter, John Baptista Riva were murdered by Royalist sympathisers on 27 May 1650, shortly after Ascham arrived in Madrid as envoy of the Commonwealth of England. The assassins were John Guillim, William Spark, Valentine Progers, Jo. Halsal, William Arnet and Henrie Progers. Henrie Progers escaped after taking refuge in the Venetian Embassy. The others sought sanctuary in a church.
In 1648 Ascham published his ‘Discourse of what is lawful during confusions and revolutions of government’, arguing that allegiance can only be owed to a power capable of protection, and that previous oaths of allegiance to someone who no longer held power were null and void. This was intended to persuade those who had sworn allegiance to Charles I, that they could in good conscience, swear allegiance to the Commonwealth.
He had acted in other diplomatic roles for the Commonwealth, and was granted a passport by Philip IV to come to Spain to deliver letters on behalf of the Commonwealth. He wasn’t technically an Ambassador, since Philip would not accept an embassy from a government which had just executed a Catholic king. However, Ascham’s murder was a violation of his passport, and so Philip wanted to be seen to take action. The proceedings of the murder trial, recorded by Agustin de Hierro were therefore sent to London, translated and published in 1651.
The assassins were seized from the church where they had taken sanctuary, tried, condemned, and then restored to sanctuary, where they were maintained by the contributions of ‘persons of quality’ until they all had opportunity to escape. Spark, the only Protestant among them, was alone recaptured and executed.