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The King's Cabinet Opened

Charles I (published by order of Parliament) · 1645

A 1645 Parliamentary pamphlet publishing Charles I's captured private letters to Henrietta Maria, revealing his secret wartime plans.

These are Charles I's own captured letters to his wife, published by his enemies to discredit him.

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Title page of a 1645 printed pamphlet titled The Kings Cabinet opened: or, Certain Packets of Secret Letters & Papers, with handwritten marginal annotations in black ink on the right side and bottom, including the words 'to their shame' and 'not onely a rebelling, but a treacherous action'. Printed in London for Robert Bostock.
The King's Cabinet Opened, London, printed for Robert Bostock, 1645.

About this source

What it is

The King's Cabinet Opened was a political pamphlet published by Parliament in 1645, during the First English Civil War. It printed letters and papers written by Charles I to his wife, Henrietta Maria, that had been captured after the Royalist defeat at Naseby.

Why it matters

The letters exposed Charles's private negotiations, including plans to bring in foreign and Irish Catholic troops to help his cause. Parliament published them deliberately to damage Charles's reputation and show he could not be trusted. The pamphlet shows how private royal correspondence became a weapon in a propaganda war, and how both sides used print to shape public opinion during the Civil War.

Look closer

  • Why would Parliament want to publish the king's private letters rather than keep them secret?
  • What does the choice of which letters to print suggest about Parliament's aims?
  • How might Charles have explained these letters if he could answer back?

This document is part of the curated material that grounds the AI version of Charles I on Humy.ai — when students ask about related events, the AI can quote it and cite it.

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