Meaning of a sentence in A History of Britain about Edward I

Question

I faced this paragraph in "A History of Britain" by Simon Schama:

In the summer of 1263 the situation became critical. De Montfort and his allies had captured most of southeastern England. Henry had retreated in fright to the Tower of London, doubtless relieved that he had added those new walls to its defences. To raise money to pay the mercenary troops in the royal army the queen had pawned her jewels to the Templars. On the pretext of inspecting or possibly redeeming them, Edward talked his way into the New Temple, where he proceeded to stage a bank robbery, smashing the treasure chests and relieving the Templars of their gold and silver. It was a classic Edwardian stunt, but its effect was to convert the mayor and burgesses of London from cool sceptics of the Montfortians into unreserved allies. What, after all, was the point of supporting the forces of order if they were themselves the leading criminals? Taken off their leash, the citizenry expressed its displeasure against the royalists in the usual ways. The fact that the queen was not only the patroness of the hated ‘foreigners’ but also enjoyed the proceeds from several prime tolls in the city made her an especially choice target. Fearing the worst, Eleanor attempted to break out of London by river and get to Edward’s army at Windsor. But her boat was recognized and pelted with stones and ordure from the crowds standing on London Bridge, the site of her most lucrative toll stations. Mortified by the humiliation, she was forced to take refuge in St Paul’s. It was an affront that neither she nor Edward would ever forget or forgive.

What exactly the emboldened part means? I don't want to know just the meaning. A bit more information on: how does it mean what it means?

Isn't it a bit ambiguous for the native speakers too?

Also I think I need a very brief background/foreground info about the incident for a better understanding.

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Edit:

For the ambiguity:

I wasn't sure what Edward I actually did. How Did he robbed the jewels? Did he stole them secretly or with force or what? Did he acted like it was some thieves (What's "smashing" for)? How they found out it was him (if the text suggests something)?

Also, "redeeming" means?

Answer 1

The word pawned means that he got a loan, leaving some valuable objects as collateral. If he did not repay the loan within a certain amount of time then the pawnbroker could keep the items.

Redeeming, in this context, means the act of repaying the loan plus any interest and recovering his collateral.

The highlighted passage means that he entered the temple, promising that he was about to redeem the loan, but then took the Templars' money by force.

And saying that he "staged" a robbery just means that he robbed them. It doesn't indicate that he made any false performance, or claimed that other people had robbed them.