the Thames Estuary, which was considered the most likely site for the expected Spanish invasion. Works included the construction of earthen ramparts around the old blockhouses at Tilbury and Gravesend, and a boom defence across the river, consisting of a chain supported by 120 ships' masts; also a pontoon bridge was constructed to allow the English army to deploy on either shore. The boom broke at the first flood tide after its completion. The exact contribution of Giambelli to these works is unknown, because he is not mentioned in any of the reports made by the Earl of Leicester, the commander of the English army in Essex; however, his name is noted in the accounts, drawing a respectable fee of six shillings and eight pence (£0.33) per day. When the Spanish Armada was attacked by fireships in the Calais roads, the panic which ensued was largely due to the conviction among the Spaniards that the fireships were "infernal machines" constructed by Giambelli; however they were unaware that he was fully occupied by the defensive works in the Thames and that a national shortage of gunpowder prevented its use in the English fireships. In 1591, Giambelli presented a plan to the Lord Burghley for a water system to cleanse the fetid ditches surrounding the City of London and another (perhaps a type of fire hydrant) which would allow fires in the City to be fought more effectively. Neither of these schemes seem to have been acted upon. Starting in 1597, Giambelli constructed a trace Italienne fortification surrounding Carisbrook Castle on the Isle of Wight; the work was mostly completed by 1600, but remodelling of two of the castle's original towers was not completed until 1603. In 1602 at the request of the Privy Council, Giambelli surveyed the fort on Plymouth Hoe, which was sited on the location now occupied by the Royal Citadel, following complaints that the defences were inadequate. Giambelli made three reports on Plymouth. He suggested surrounding the town with a wall with nine ravelins. He is said to have died in London, but the year of his death is unknown. References 16th-century births Italian military engineers Military personnel from Mantua Italian emigrants to the United Kingdom Year of death unknown