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The Drake Exploration Society

Francis Drake's treasure haul 29 April 1573

John Thrower

A track near Nombre de Dios

The Camino Real looking north from the
most southerly point of the ambush site

When fifteen English led by Francis Drake and twenty French led by Guillaume Le Testu successfully ambushed a 190 mule-train near Nombre de Dios, they must have been truly amazed to see such a massive amount of gold and silver bullion: riches beyond their wildest dreams. They carefully collected all the gold which was in various forms of bars, quoits (heavy discs) and coined metal. Most of the gold would have been of 22 carat purity. Unable to deal with the enormous weight of silver, they buried as much of this they could, about fifteen tons, before the return of the Spanish guards with reinforcements from Nombre de Dios.

Some twenty years later, Drake edited the English account of this ambush which was "faithfully taken out of the reports of Christopher Ceeley, Ellis Hixon and others" by Philip Nichols, Preacher. Drake was quite specific about the amount of silver on the mule-train, which he estimated to be about thirty tons, but which he was forced to leave mostly behind. He was curiously reticent, however, about the amount of gold that the raiders had carried off:

"and being weary, we were contented with a few bars and quoits of gold as we could well carry."

This is a definite Drake joke or "leg-pull" at the expense of the reader, of which there are a number in the account! However, there is more than a hint here about the problems they faced in carrying off the heavy metals.

Drake's account was finally published, by his nephew, in 1626 as Sir Francis Drake Revived. Amazingly, it was not until more than 300 years later, in 1932, following the painstaking work of Irene Wright in translating the carefully stored records in Seville, that the English, Spanish and later the French accounts could be matched and discussed together. Even so, most major Drake historians since 1932, have not troubled to evaluate one of the most important points - the weight of gold that the raiders had secured. This weight tells us everything about the hard task Drake's and Le Testu's men had to accomplish to return twenty-one miles through coastal jungle, to the River Francisco.

The Spanish records allow us to penetrate Drake's reticence - they give a maximum figure of 130,000 pesos for the gold on the mule-train. But, what was the weight of all this gold? The peso, in this case the peso de oro, was a measure of weight of 22 - carat gold. It was equivalent to one hundreth (0.01) of a Spanish pound weight. In its turn, the Spanish pound weight was slightly heavier than the English pound avoir - 1.014 lb. Thus the 130,000 pesos of gold on the mule-train weighed an astonishing 1,318 lb - well over half a ton!

There is another useful method by which one may cross-check on this figure. The Elizabeth I £1 coin was also minted in a known weight of 22 - carat gold, a 0.0249 lb avoir. Since the peso de oro was worth 8s 3d in 1573, a value mentioned in Sir Francis Drake Revived, a simple calculation gives 1,337 lb for the 130,000 pesos - a good agreement with the above figure, considering the accuracy of minting in those days.

Over half a ton of gold meant that the English and French were quite sufficiently burdened with gold alone. They could not possibly carry awkward silver bars as well - heavy for their value - though, no doubt, some tried to do so. The silver would have been for the allies, the Cimmarones to carry. We do not know how many Cimmarones were with Drake's party, but even if there were as many as forty, they would have had severe difficulty in carrying away as much as two tons of silver. The gold represented a full load for four mules. So, the remaining 186 mules were carrying 300 pounds of silver each, amounting altogether to 55,800 lb, some twenty-five tons. One can readily understand how it was that the returning Spaniards found so much just lying around.

What was the value of Drake's treasure haul? Of course one can calculate the modern value of the weight of gold - some £3.5 million for 100,000 pesos. However there are several problems here. Most important is that the gold today is much less valuable than it was in the 16th century. Also the gold price varies significantly from day-to-day and substantially from year-to-year. Although the price has risen sharply in the present period of uncertainty, it has been at a relatively low level in recent years. It is worth less now than it was ten years ago, when I first made some of these calculations! The value of the pure gold in an Elizabethan £1 coin was a measly £86 ten years ago; it has now fallen to £79. This makes a nonsense of an attempt to compare values on this basis and does not even begin to reflect inflation since the 16th century.

Various Drake biographers and other historians have made estimates at different times, each trying to relate Tudor versus modern values at the date of publication. Inevitably these rapidly become dated. A recent example is Alison Weir's book - Henry VIII, King and Court, she uses a factor of 300 to convert £1 Tudor to modern value in the year 2000. This factor works well for some items but is less suitable for others. 300 is an overall average; some Tudor products were relatively more expensive than today and others cheaper. For example, if one were to employ a factor of 300 to convert the £3,400 that Francis Drake paid to purchase Buckland Abbey, today's price would be £1,020,000 - much too low - a factor of at least 1,000 and probably more would be needed Looking back to Drake's 1573 gold, 130,000 pesos, corresponds to £53,625 Elizabethan. Of course he was obliged to share this with the French, but we know that the English, ultimately had the larger share. The total sum, on its own would have been sufficient to purchase Buckland Abbey sixteen times over! This may sound fantastic, but perhaps gives a better feel for the value of the treasure to Francis Drake. It was the turning point of his career, He gained influence, and it made possible the building of the Golden Hind. Clearly there has to be an advance from the overall multiplying factor of 300 discussed above - perhaps to at least 400 which would value the total treasure haul to well over £20 million today.

The factor to convert value will go on increasing into the future. However one thing remains constant, that is the shear weight of very heavy gold, twice as dense as lead, with which the raiders had to struggle over steep hills, across rivers and through jungle, in torrid, sticky heat back to the Rio Francisco.

Weight and Value of Gold and Silver on Mule Train


Gold weight calculation based on:

  1. The weight of the gold peso (peso de oro) 22 carat gold. This is defined as one hundreth (0.01) of the Spanish pound = 1.014 lb avoir.
  2. The comparative weight of the gold peso to that of the Elizabeth I £1 coin (22 carat) since the peso was worth 8s 3d i.e. 0.4125 £ Elizabeth I.

Gold weight (22 carat) on mule train

  1. 100,000 pesos = 1000 x 1.014 = 1,014 lb avoir
    130,000 pesos = 1300 x 1.014 = 1,318 lb avoir
  2. £1 Elizabeth I = 174.5 grains 22 carat gold
    Gold peso = 174.5 x 0.4125 = 72 grains 22 carat gold (7,000 grains = 1 lb avoir)

100,000 pesos = 7,200,000 ÷ 7,000 = 1,028 lb avoir
130,000 pesos = 9,360,000 ÷ 7,000 = 1,337 lb avoir (half a ton 1,120 lb)

King's gold recovered by Spaniards

11 gold bars, 6,300 pesos = 65 lb

Modern value of pure gold (round figures)

  Troy oz Elizabethan pound Gold peso 100,000 peso
January 1994 £258 £86 £36 £3,600,000
November 2004 £238 £79 £33 £3,300,000

Modern value of pure silver (round figures)

  Troy oz 55,800 lb
January 1994 £42 £2,343,000
November 2004 £42 £2,343,000


Amount and value of gold in the Elizabethan £1 coin (not the sovereign which was worth 30s in Elizabeth I reign.) and on the comparative value of the Elizabeth I £1 coin with the Spanish gold peso. (Several authors note the gold peso to be about 8 shillings Elizabeth I in the 1570s, John Sugden is one example.)

£1 Elizabeth I = 174.5 grains of 22 carat gold

The modern value of gold in Elizabeth I pound = (174.5 x 22 x 258)/( 480 x 24) = £86

(NB 1 Troy ounce = 480 grains = £258 in Jan 1994)

12 troy ounces = 1 lb Troy (14.58 oz Avoir)

1 gold peso = 8 shillings Elizabeth I = 8.25 / 30 x 174.5 = 72 grains

22 carat gold = £35.5

Gold on mule train

Spaniards recovered 11 gold bars belonging to king valued at 6,300 pesos

1 gold bar value was 573 pesos = (573 x 72)/480 = 85.9 Troy ounces = 5.9 lb

Silver on mule train

There were 190 mules, Since 4 were carrying gold, then 186 were carrying silver.

186 carrying 300 lb silver bars each = 186 x 300 = 55,800 lb or about 25 tons.

Modern value 55,800 lb at £58 (Nov 2004) £3,236,400

Number and size of silver bars

Take 50 lb as an example of the weight of 1 silver ingot.

Then there were 55,800/50 = 1,116 bars on mule train

Francis Drake buried 15 tons = 33,600 lb = 33,600/50 = 672 50 lb bars

Volume of 50 lb silver bar = 2,250 cubic centimetres

So if a bar is 30 cm long than width is 7.5 cm depth 10 cm or 1 foot x 3" x 4½"

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