In the early modern period, it was necessary in Europe because at that time coinage had an intrinsic value and even though a town was besieged commerce had to continue and soldiers had to be paid.
Not sure as to why the shape, might be ease of manufacture or somesuch.
All the coins issued from Newark are struck upon lozenge-shaped flans, which flans were apparently cut directly from the dishes, trenchers, and other varieties of silver plate, in the town
So yeah, ease of manufacture. Plus that cutting circular blanks would have left the space between as either waste or material that would need to be reprocessed.
Money minted during a siege.
https://en.wikipedia.org/wiki/Siege_money
Not sure as to why the shape, might be ease of manufacture or somesuch.
For some reason I thought it was the besiegers that needed this
https://en.wikipedia.org/wiki/Siege_money_(Newark)
So yeah, ease of manufacture. Plus that cutting circular blanks would have left the space between as either waste or material that would need to be reprocessed.