This source, "Men of Wealth" by John Flynn has the background to the episode Armstrong describes.  I know of no source that gives the specific date of the uprising.
No canvas designed to depict the dawn of capitalism would be 
complete without a brief place for what was perhaps the first 
authentic strictly capitalist depression in Europe, produced largely 
by the operations of these new bankers. The episode is generally 
known as the failure of the Bardi and Peruzzi banks in Florence 
and it produced consequences not unlike those attending the fail- 
ure of Jay Cooke in America or Baring in England or the Credit 
Anstalt in Vienna in 1931. 
Florence had carried far the organization of her producing 
energies. Wool textiles was one of her important products. The 
homes of the townspeople and the villagers were turned into sweat- 
shops to which the merchants sent the raw wool to be processed in 
the homes. While the Church and her doctors thundered against 
interest and profit, the village priests read pastoral letters threat- 
ening the workers with a denial of the sacraments if they resisted 
the exactions of the wealthy usurers of Florence who dominated 
the system. 
A continuous supply of raw wool on the one hand and wide 
markets on the other became essential to the city's economic 
safety. This probably led the Florentine banker-traders to Eng- 
land, where the best wool was produced. Two of the greatest 
Florentine houses, the Bardi and the Peruzzi, began extensive 
operations in England in the latter part of the thirteenth and the 
beginning of the fourteenth century. They made large loans first 
to Henry III and later to Edward II and Edward III, but mainly 
to the latter. In return they got the privilege of trading in England, 
which was otherwise closed to foreign merchants, and the privilege 
of buying wool for the Florentine market. 
It is these loans to Edward III which are called by historians 
the cause of the failures of the Bardi and Peruzzi. But this is a 
very considerable oversimplification. By 1337, when Edward III 
launched that bootless century of struggle known as the Hundred 
Years' War by invading France, he owed the Bardi 62,000 pounds 
and the Peruzzi 35,000 pounds. But he immediately made enor- 
mous additional loans to finance his ambitious design to seize the 
crown of France from Philip VI. By 1343, when the first phase of 
that quixotic adventure came to an end, he is said to have owed 
900,000 pounds to the Bardi and 600,000 pounds to the Peruzzi. 
Sapori, a recent student of this historic episode, thinks the sums 
exaggerated and that they were nearer 500,000 and 400,000 pounds 
each. 
Edward had promised to pay the principal and interest of these 
loans in coin, and his undertaking was guaranteed by the Arch- 
bishop of Canterbury and the Bishop of Lincoln. So eager was 
the rash Edward for these sums that, upon completing the arrange- 
ment, Edward gave to "the merchants of the Bardi society" 30,000 
pounds sterling, to the "merchants of the Peruzzi society," 20,000 
pounds sterling, and "in consideration of the great help given the 
king," 500 marks to a Peruzzi agent in England and, for the same 
reason, 500 marks to the wife of another agent and to the wife of 
a Bardi agent. Wives of two other agents got 200 pounds each. It 
sounds as if two great American banking houses managed an 
American loan to the government of Chile on a 20 per cent basis,
while the partners in the two banking houses got a several-hundred- 
thousand-dollar bonus from the Chilean president, who also dis- 
tributed the largess among the South American agents of the 
banking houses and their wives. Thus, commercial bribery had 
already made its way into the investment banking business. 
But all this time Florence, rushing forward in the first incident 
of uncontrolled expansion of the capitalist era, was moving deeper 
and deeper into debt. Merchants were making profits and deposit- 
ing them with the Bardi, the Peruzzi, the Mozzi, the Frescobaldi, 
the Scali, and also investing in various bond issues underwritten 
and managed by these houses, but chiefly by the Bardi and 
Peruzzi. Competition with their wool industry was growing from 
England and the Flemish weavers. But as they produced ever 
more they were ceaselessly seeking to expand their markets. Flor- 
ence, an economic unit like modern England, imported raw ma- 
terials and exported finished products. She enjoyed her expansion 
through the strategic activities of her rich bankers, who grew 
wealthy milking European monarchs and princes and at the same 
time using their loans as weapons to force Florentine products into 
those old custom-sealed European countries and cities. 
One market, among others, was of great value to Florence — the 
city of Lucca. This city was a commercial battleground between 
the merchants of Florence and Pisa. And out of this situation it 
became the victim of an episode that depicts strikingly the inheri- 
tance of violence that deformed the early struggles of primitive 
capitalism. A band of German mercenaries seized Lucca and offered 
to sell it to the city of Pisa. Pisa agreed to pay 60,000 golden florins 
and made a down payment of 13,000 florins, which it was destined 
to lose when Florence armed to balk this sale of its valued market 
to its chief rival. Later certain Florentine merchants and bankers 
— including beyond doubt Bardi and Peruzzi — offered the German 
mercenaries 8o,oco florins. They would thus control Lucca as a 
market for their products and own its customhouses and its tax 
revenues. It was as if a few leading merchants and manufacturers 
of Philadelphia were to propose to buy Pittsburgh from a mutinous 
regiment of the New York National Guard that had seized the 
latter city and was now peddling it around the East. But Florence, 
still ruled by the remnant of the old Guelph spirit, protested against 
this immoral purchase of a city's population like so many slaves. 
Finally the captors of Lucca knocked the city down to a Genoese 
merchant-adventurer named Gherardino Spinola for 30,000 florins. 
The outcome of this was war between Florence and Pisa. 
The first effect of the war was a demand for war loans, which 
the banking houses were called upon to float. And this came at a 
time when Edward III was marching his armies around Flanders 
and making new appeals for larger advances from the Bardi and 
Peruzzi. 
The competition of the English and Flemish wool weavers had 
been undermining the trade of Florence much as the competition 
of the Carolinas cut into the business of the New England textile 
industry and as the competition of the East cut into the textile 
industry of Manchester. Production in Florence fell off. The streets 
were filled with the unemployed. Merchants who had large deposits 
with the Bardi, the Peruzzi, the Frescobaldi, and others were call- 
ing for their funds. Some of the smaller bankers failed. Indignation 
against all the bankers was rising. Florence faced a crisis not 
unlike that which faced America in 1933 or Germany in 1932. 
Nothing could save the great bankers but a moratorium. Disturb- 
ing rumors floated in from Flanders, where Edward's generals were 
having but small success. In this crisis this old city, where the 
popular party had always been strong, with its active popolo 
minuto, which hated the Ghibellines not only because they repre- 
sented the philosophy of the economic royalist, but of external 
interference and domination, submitted to the device of dictator- 
ship. In 1342 that fantastic adventurer, Walter of Brienne, a 
Frenchman who styled himself the Duke of Athens, was made 
dictator through the machinations of the bankers. He proclaimed 
a moratorium on private debt for three years, which saved them. 
But, having come into power, he plotted immediately for com- 
plete mastery. He suspended payment of the interest on the public 
debt and planned gradually to extinguish it by progressive repu- 
diation, which promptly brought upon his head the wrath of the 
bankers. In 1343 the distress of the city was so great, the fortunes 
of the war so melancholy, the anger against the dictator so general 
that the people poured into the streets in an unrestrained uprising. 
They looted the palace of the Bardi, taking it is said, valuables to 
the amount of 30,000 florins. The dictator was compelled to resign 
and flee from the city. Certain Neapolitan bankers who had loans 
outstanding in Florence called them. The news came of Edward's 
reverses that brought the Hundred Years' War to its first pause in 
1343, and Edward delivered the crowning blow by defaulting upon 
his loans. Immediately the Peruzzi bank failed. And within a year 
the great Bardi bank crashed. They carried with them most of the 
bankers of Florence. The disaster shook all Europe and produced 
in those cities where capitalist organization had proceeded to any 
length, such as Venice and Genoa, the most depressing conse- 
quences. Excessive debt, overexpanded industry, concentration of 
money and power and wealth, the extravagance of governments, the 
destructive power of war had made for Europe its first great capi- 
talist depression in the modern era.