On 22 August 1849, the Republic of San Marco surrendered to Austria. The Republic was formed after a revolt in Venice against Austrian rule in March 1848. The Austrians eventually besieged Venice, leading to starvation and outbreaks of cholera in the city. During this siege, they launched the first air raids in history, by unmanned balloons which floated over Venice carrying bombs. The British press didn't take any notice of this at the time, but the following account appeared in the Morning Chronicle a week after the surrender:
The Soldaten Freund publishes a letter from the artillery officer Uchatius, who first proposed to subdue Venice by ballooning. From this it appears that the operations were suspended for want of a proper vessel exclusively adapted for this mode of warfare, as it became evident, after a few experiments had been made, that, as the wind blows nine times out of ten from the sea, the balloon inflation must be conducted on board ship; and this was the case on July the 15th, the occasion alluded to in a former letter, when two balloons armed with shrapnels ascended from the deck of the Volcano war steamer, and attained a distance of 3,500 fathoms in the direction of Venice; and exactly at the moment calculated upon, i. e., at the expiration of twenty-three minutes, the explosion took place. The captain of the English brig Frolic, and other persons then at Venice, testify to the extreme terror and the morale effect produced on the inhabitants.
A stop was put to further exhibitions of this kind by the necessity of the Vulcan going into docks to undergo repairs, which the writer regrets the more, as the currents of wind were for a long time favourable to his schemes. One thing is established beyond all doubt (he adds), viz., that bombs and other projectiles can be thrown from balloons at a distance of 5,000 fathoms, always provided the wind be favourable. 1
Some comments. It's hard to find reliable information on these attacks. The best account I've seen is by Lee Kennett and he's not sure how many balloons were released, saying that the largest number he has seen is two hundred.2 This doesn't fit well with the Morning Chronicle article, which seems to suggest that only two balloon bombs were ever launched. This is supposedly based on a letter written by the inventor of the balloon bombs, Franz von Uchatius, so if it's accurate should be preferred over secondary sources.3
But whether the number was two or two hundred, it doesn't seem like the balloon bombs had much effect on the course of the siege, which went on for another five weeks -- despite the reference made in the Morning Chronicle to 'the extreme terror and the morale effect produced on the inhabitants'. That was clearly what was intended, as the bombs were released (or maybe detonated) by a timer, and couldn't possibly hit specified targets from a balloon drifting above the city.4 More importantly, the bombs used were filled with shrapnel, which isn't much use for anything but killing and maiming people. So there were few qualms on the part of the Austrians about targeting and killing civilians. Which they went on to do with presumably much greater efficiency when they later bombarded the city with more conventional artillery, averaging a thousand shells a day.5
Finally, the air raids of 1849 seem to have had as little impact on the wider world (at least the English-speaking part of it) as they did on Venice. As noted above, there was very little notice taken in the British press, and I've come across only one meager reference to Venice in books published before 1914 (and that in a book translated from the German, written by the German military balloonist Hermann Moedebeck). So it doesn't seem like they inspired anyone to find a better way to bomb cities from the air; that was an idea which had to be invented all over again. Which it was, of course, and Venice's next air raid was on 24 May 1915.
Morning Chronicle, 29 August 1849, 5. ↩
Lee Kennett, A History of Strategic Bombing (New York: Charles Scribner's Sons, 1982), 6. ↩
Kennett does state that two bombs were used in the first armed test, but that this was carried out on 12 July, with another 'series' of tests on 15 July. ↩
Which is not to say they were just released at random; the balloon-bombardiers had to take windspeed into account when calculating how long to set the timer for, so that it would go off over Venice -- though the wind could then change direction after launch, of course. ↩
Lawrence Sondhaus, Naval Warfare, 1815-1914 (London: Routledge, 2001), 47. ↩