The Grand Canal, painted by Joseph Mallord William Turner.
Part 1 - Roots
Little communities of sailors, fishermen, salt-producers, and merchants populated the coast of Veneto and the islands close to it in Roman times yet. These villages were sort of prolongation of the bigger inner cities, in particular Padova (Padua) and Aquileia.
Their advantage was the fact of being situated along the shortest way between Aquileia and Ravenna. Population growth and first social organizations in the lagoon came from Byzantine re-conquest of Italy, formerly occupied by Ostrogoths (535-553) and, afterwards, because of Lombard invasion (568). From that moment on, in fact, more and more people fled the inner lands, menaced by Lombards, and went into the coast and into the islands, which were protected by Byzantine, thus forming in Cittanova (present time Novigrad, in Croatia), located where ancient Eraclea was; a first bigger center, where a Byzantine magister militum (master of the soldiers) was residing.
At that time, locally elected Sea Tribunes of the Imperial era with administrative powers still existed.
When Byzantine power in Italy became weaker, between VII and VIII century, the government of the area passed on a local magistrate called doge (local dialect variation of the Latin dux - leader). The doge was still formerly responding to Constantinople through the Ravenna's Exarch. The first two doges, Paoluccio Anafesto (697-717) and Marcello Tegalliano (717-726) are still quite obscure.
The third one, Orso Ipato (726-737), rebelled from Constantinople for not accepting iconoclasm. He eventually surrendered and was murdered. For 5 years, the doge was replaced by a magister militum (737-742), strictly controlled by the Exarch.
On 742 the dogato (government of the doge) was restored , and the political center became Malamocco.
When, the Exarchate fell in 751, the relation with Constantinople became looser and looser, just a formal homage of "suzerainety" to obtain the protection of Mediterranean largest sea power in exchange.
When the Franks overcame the Lombards (774), some wanted to plede submission to Charlemagne, but others preferred to remain loyal to Constantinople. The latter prevailed, Pippin's attempt to conquer the area failed (803-810) and a treaty was signed by Charlemagne and Imperator (Emperor) Michael I Rangabé, stating the sovereignty of Constantinople on Venetia and Dalmatia (812).
During this crisis, or just afterwards, under doge Agnello (Angel) Partecipazio I (or Particiaco, 809 or 810-827), the government was definitively transferred into Rialto(Rivoalto), the future core of modern Venice.
According to the tradition, in 829 Buono da Malamocco and Rustico da Torcello carried from Alexandria the relics of Saint Mark, the future protector of the city.
During the IX (9th) and X (10th) century, the dogato became a life-long elective charge, against the will of those like the Partecipazi, Candiano and Orseolo families who wanted it to became hereditary. Venice established good relationships with the Holy Roman Empire (Pactum Lotarii, 840), and consolidated those with the Byzantine one, while fighting against Arab and Slavic Pirates.
New immigrants due to Hungarian incursions made the city grow , and Venice adopted an expansionistic policy in order to acquire better control over food and raw material supply, and commercial routes. Pietro II Orseolo (992-1009),
by conquering the islands of Lissa, Curzola and Lagosta, formerly dominated by pirates, established the dominance of Venice on Dalmatia and nearly all the Adriatic, hence his titles of "duke of Dalmatia and Croatia", and Byzantine "delegate border defender".
This conquest was celebrated with the Sposalizio del Mar (wedding with the Sea) on Canal Grande. Today this parade is included in Regata Storica (historical regatta) every August.
During XI (11th) century, Venice, together with Constantinople, struggled to limit the Norman expansion, and the Byzantine Emperor rewarded the city with large commercial privileges valid in his empire. Neutral in the Holy Germanic Roman Empire struggle for the crown, Venice obtained the freedom of commerce with all Italy and Germany by Henry IV (1095)
Please observe that during the XI century, Venice was considered among Byzantine territories and dependencies (pink). But on the other map, which is about the XII and XIII centuries Venice is considered independent, whilst allied to the Byzantines. Please notice the Dalmatian territories too. (Map Source: http://www.fordham.edu/halsall/maps/11citaly.jpg)
Part 2- the end of good relationship with Constantinople
Mariner republics and Hansa commercial routes
In order to conserve its competitive position with regards to Genoa and Pisa, Venice took part to the first crusade (conquest of Haifa, 1100);
But, since the Venetians considered the advantages those two rival republics given to them by Emperor John II Comnenos to be unfair, they interrupted their alliance with Constantinople.
Under the dogato of Domenico Michiel (1118-1129), Venice Conquered and/or pillaged several Byzantine Islands until Constantinople accepted to restore the former privilege towards Venice in 1082, andrights on Crete and Cyprus (1126 treaty).
In the same period, Venice conquered Ascalona from Muslims in Syria, took part in the conquest of Tyro, and obtained from King of Jerusalem Baldovine II of Bourg the right to establish permanent colonies with the extraterritorial privilege.
Venetian had little strategic possessions that clustered the East Mediterranean, (the main ones were in Constantinople, Salonika, Corinth, Cyprus, Crete, Ionian Islands, and, in Syria, at Ascalona, Kaipha and Tyro). Unfortunately for the Venetians, the Pisan and Genoan, their rivals and competitors, also had a similar net of controlled places.
Flags and trade routes of the four Mariner Republics: from left, Venice, Genoa, Pisa and Amalfi.
Venice managed, afterwards, to obtain even more privileges in the Byzantine Empire 1148, and also in the Norman reign of Sicily (1155).
During the second half of the XII century, Venezia was menaced by the Emperors Fredric I " Barbarossa" (of Germany - later: Holy Roman Empire) and Manuel I Comnenos (of the Byzantine Empire)
Against the former, Venice remained loyal to Pope Alexander III, and participated in the first Lombard League (an alliance of Italian towns against Barbarossa). Because of its excellent diplomatic policy of equilibrium between the West Emperor and the "comuni", after Legnano (1176), Venice was entitled as mediator. ("convegno di Venezia" , 1177, doge Sebastiano Ziani)
As to Venetian-Byzantine relationship, it was ruined by Manuel I 's ambition on the city of Ancona. A strong xenophobic movement occurred in the Byzantine Empire and this caused Venetians to be arrested, and their goods were requisitioned or damaged. The Byzantines sent a fleet, but it was repelled (1172). Finally the peace was agreed in 1175, and confimed by Emperor Andronikos Comnenos (1183); But the relations between Venice and Constantinople were not normal anymore.
During such "double crisis", some institutional reforms were approved in the city even against strong oppositions. The doge Vitale II Michiel (1172) was murdered, but a new political figure, the "pregadi", took place, and starting from the XIV cent., it formed the Senate. The People's Assembly, which traditionally was responsible for the most important decisions, was replaced by the "Maggiorconsiglio" (Council of the Elders). The latter could nominate public authorities (including the doge) and the selection of topics to subject to popular approval. The People's Assembly was limited to confirm laws that were yet decided. Such was the origin of aristocratic constitutions that became typical of the Republic. The doge, counselors, and every magistrate were elected and subject to strict controls.
Part three -- from XII to XIV century
At the end of the XII cent., the role of Venice in the world was diminished because of a sequence of unfavorable events: 1) Slavs, Hungarian and Normans promoted many insurrections all along the East Adriatic coasts. 2) Constantinople was behaving ambiguously with Venice, with the clear intent to create a sort of equilibrium between its power and that of the other sea republics, Pisa and Genoa, so that no one could be strong enough to seriously menace "Nova Roma" 3) After the Muslim conquest of Jerusalem, the Venetian properties in Syria appeared compromised.
The Serenissima(*) overcame this situation with the fourth crusade (1202-1204).
(*) La Serenissima: This title, litterally meaning "The Very Serene One" was that which all the major magistrates of Venice, including the Dogi (plural of Doge), used for themselves and their republic.
Just because of Venetian initiative, it diverted from its original plan to invade the Muslim owned "Holy land", to the conquest of Constantinople. After the capture of Constntinople came the partition of the Byzantine Empire and the formation of the East Latin Empire (of Constantinople), with included enormous advantages for Venetia.
While the republic limited its occupation to some strategic positions in Epirus, Morea, Crete, Euboea (Evvoia), several Venetian patricians made their own dominions in the main Aegean islands as vassals of the Republic itself. By this, a dense cluster of colonies was formed, creating a sort of "Empire of Romanìa", including the main part of the former Byzantine Empire, that gave to Venetian merchants a virtual commercial monopoly, even though Pisan and Genoan, as well as the remaining Byzantines, tried all they could to contrast it. This situation ended in 1261, when Michael VIII Paleologos recaptured Constantinople for the Byznatines and destroyed the Eastern Latin Empire.
The Venetians then found themselves to be less privileged than Genoese, who were the new allies of the Eastern Empire, so they tried to re-conquer Constantinople (with the help of the Angiò's of Naples), but only with partial success. Thereafter, the Serenissima had to front the Ottoman Turks, so it started new negotiations with Byzantium and, by the end of the XIV century, it reacquired lands in the East that had been lost in 1261.
During the same period, Venice fought nearly without pause against Genoa (1261-1270, 1294-1299, 1351-1355, 1378-1381). The most violent war was the one called "of Chioggia", which ended with the peace of Turin (1381). After that, Genoa started to decline and Venice could return to its former unrivaled political and economic activities in the East.
Also in this period, The Serenissima, through agreements with Muslim powers, obtained important positions in Egypt and Syria, where caravans coming from India had their traditional home bases. The portrait of the traitorous Falier was removed from official Dogi gallery as a sign of scorn
During the XIII and XIV centuries, the main constitutional reform was the closing of the Maggiorconsiglio (1297), with which the Republic became decidedly oligarchic. This change, opposed by a strong party, was the cause, in 1310, of a conspiracy (Conjure of Tiepolo) that was repressed.
In order to protect the new political system, the "Council of Ten", which was a secret tribunal with its own secret police, was created. Subsequently, this Council's powers were augmented more and more. It was meant to be a temporary one, but it was made permanent after the conspiracy led by the doge Marino Falier (or Faliero) in 1355.
Since many local Lords were competing for supremacy overa all over Veneto and Lombardy, Venice understood the need to expand into the countryside.
La Serenissima repubblica took part in the Florence-Milan League (1337-1339), which caused the ruin of the power of Mastino II Della Scala. Venice obtained Treviso (1339, definitively confirmed in 1389), Ceneda (definitively in 1338) and Castelfranco.
Later, after defeating the da Carrara family of Padua, Venice occupied Padua, then Vicenza and Verona (1404-1405), and, once brought Dalmatia to submit (1409-1437). Venice conquered nearly all of Friuli (1420), hence ending the state of the patriarch of Aquileia.
At one time, a party arose and judged the policy of conquest in the countryside dangerous and not so advantageous. It was suspended for some time, until doge Francesco Foscari (1423-1457) strongly revived it in order to contain the dynamic expansionism of Filippo Maria Visconti, duke of Milan.
Venice, allied with Florence and other communes, subtracted the eastern Lombardy from the Visconti (Brescia and Bergamo in 1428, Crema in 1447), and Ravenna from the da Polenta (1410-1441).
When Filippo Maria died, Venice tried to conquer Milan, but Francesco I Sforza managed to stop it, since Florence left the alliance with Venice and allied with him.Therefore, between Milan and Venice the peace of Lodi (1454) fixed the border between the two states along the river Adda. When the Ottomans advanced in the East and Conquered Constantinople in 1453, Venice embraced the policy of equilibrium of Powers.
Venice: Part four -from the second half of XV century to the beginning of XVII. After the Ottoman conquest of Constantinople (1543),
Venice had to fight vigorously in order to defend its possessions in the East, which were menaced by Ottoman Turks since 1430 (Salonika).
At first the Negroponte was lost (1470), and while it could conserve Cyprus (1474), after many wars, during which the Ottomans reached Friuli, Venice lost Morea (1460), Lemnos (1477), Most of Albania (XV÷XVI cent.), Modon and Koron (XVI cent.).
Meanwhile, the discovery of America and a new way to Far East through Africa caused a deep change (actually not entirely negative) on Venetian economy and general politics.
The Serenissima won the Ferrara war (1428-1484), gaining Rovigo and Polesine (North Lombardy) at Bagnarolo peace (1484), took part in the Holy League against Charles VIII (1495) and managed to help the Aragonese in assessing their control on the Reign of Naples, where Venice had important interests related to the ports of Apulia. Then, together with Louis XII of France, Venice attacked Milan, temporarily conquering Cremona and Ghiara d'Adda (1499-1509), and occupied also some imperial lands, such as those of Trieste and Gorizia (1508).
This expansion worried the other power and during the same year the Cambrai league (alliance formed by Holy Roman Emperor Maximilian I, King Louis XII of France, Pope Julius II, King Ferdinand V of Aragón, Hungary and several Italian city-states) was formed, with the precise intention to dismember that that was deemed the strongest Italian Power, Venice. Venice was defeated at Agnadello (1509) and had to leave some of its possessions in Lombardy and Veneto.
But the "Very Serene Republic" did not surrender: on the contrary, it used its refined diplomacy playing on the discordance inside the League, eventually managing to make it break down. Moreover, Julius II created a new one, the Holy League (1511), with the purpose to drive French away from Italy. The allied forces -Papal, Venetian, and Spanish- overcame the French, and Venice recovered most of the territories it had lost (1512)
Then it allied again with Louis XII (Blois, March 1513) against the League of Malines in order to conquer Milan, but the attempt was unsuccessful. Venice was neutral when Francis I, who succeeded Louis XII, conquered it on 1515. Anyway, the treaty of Noyon (1516) between Francis I and the new king of Spain, Charles of Absburg (the future Emperor Charles V), gave back to Venice former territories remaining in Veneto that were not recovered yet.
Venice did not substantially take part in the following struggles among France, Spain and the Empire for the control of Italy. It was busy to defend its oversea possession against Ottoman Turks, who took away most of the Aegean Islands and some strategic ports (1537-1540). Later, Cyprus was lost too, after the Heroic but useless resistance of M. Bragadin at Famagusta (1571).
The Holy league, wanted by pope Pious V, managed to obtain a great naval victory against the Turks near Lepanto (1571 -- please read this thread for more information), but Venice obtained no practical gain from it. Its possession were reduced to Crete, few Aegean and Ionian Islands, some harbors in Albania and Greece, and Dalmatia, this latter in continuous danger.
Since Spain had won the control of Italy, Venice remained neutral in order to safeguard its independence. From 1605 to 1607, the senate strongly polarized with Pope Paul V (incident of the interdict), who was disputing the full sovereignty of the republic and, interdict notwithstanding (1606), the Venetians prevailed.
Part five - The decadence during XVII and XVIII centuries
As soon as it overcame the Uskoks (Slav Pirates) in the Adriatic Sea with the help of the Austrian Absburgs (1617), Venice had to face many Spanish plots. A Spanish ambassador, the marquise of Bedmar, was suspected for a conspiracy from 1611 to 1612, together with the Venetian gentleman Angelo Badoer, who had been exiled for collusion with Spain. Then, in 1617, another conspiracy, this time by Captain Alessandro Spinosa, that who would have given the city of Chioggia in the hands of Spaniards, was halted in time. Finally, in 1618, another plan, probably by the same marquise of Bedmar, according to which Venice should be invaded and put on fire by mercenary troops, was equally thwarted.
Thereafter, The Serenissima, allied with France and the Duke of Savoy, prevented the occupation of Valtellina by the Absburgs (1620-1626).
A tremendous feat followed, which took shape in the War of Crete (1644-1669). This was for the defense of the only remaining important Mediterranean dominion against an Ottoman attack. The war was fought not only on the island, but also on the sea and in the Dardanelles, where Venetians won some battles, but they, exhausted and helpless, eventually had to surrender the islands into the Turks' hands.
During the Holy League war, Francesco Morosini, who was the last defender of Crete, managed to win back Dalmatia, Peloponnese (Morea), and some Greek ports and islands (Karlowitz, peace, 1699) from the also declining Ottoman Empire Unfortunately for the Venetians, parts of those conquests were lost in the subsequent anti-Turkish war (1714-1718), which ended with the Passarowitz peace.
Venice still kept Dalmatia, the Ionian Islands, the "Bocche di Cattaro" and some other fragments of its former empire.
We can see that Venice and the Ottoman Empire behaved not differently from The Byzantine and the Persian Empires. They fought each other during interminable wars, with the result of weakening each other, till some external powers gave them the coup de grace.
The Settecento was characterized by the splendid and sumptuous decline of the "Very Serene Republic", which remained till the end as a callous administrator of its own little oversea patrimony, and of its larger continental one, always most acculturated, cosmopolitan and pleasant, but unable to take initiatives contrasting with its century old traditions, i.e. to find allies in Europe more and more subjected to deep transformations.
Venetian golden earrings dated XVIII century
Sixth and last Part- From French occupation to joining the Kingdom of Italy
At the end of the XVIII century Venice made one last attempt to restore its old prestige in the Mediterranean with military expeditions against Muslim countries. This included the noticeable but fruitless the war with Tunisia (1784-1792) -- The Eyalet of Tunus, which was a semi-autonomous province of the Ottoman Empire, at that time.
The French Revolution surprised Venice in an "unarmed neutrality" position. It had to see French and Austrians fight each other on its land during Bonaparte's Italian Campaign (1796-1797). When some sporadic revolt against the French occurred (Pasque Veronesi), because of Bonaparte's reaction, Venice's aristocratic government, and the last doge, Ludovico Manin, abdicated (May 12th 1797); thus leaving on its place a Francophile municipality, which created a short-lifed democratic government.
A little later, with Campoformio peace (October 17th, 1797), Bonaparte ceded Venezia and its countryside up to Adige river to Austria. Venice (as well as Verona and other Cities of Veneto) expressed its rancor in form of tumults, but they were quickly repressed.
Victor Emmanuel II, King of Sardinia
After being robbed of many artistic treasures by the French Army, Venice was occupied by Austrians from January 1798 'till December 1805, when it was annexed to the Italic Reign in force of the peace treaty of Presburg.
As soon as Napoleon was defeated , the Austrian occupied it again on May 1814, and the following year it became the second main center, after Milan, of the new Lombard-Veneto Reign that was under the sovereignty of the Empire of Austria.
In 1821 the first great trials against the "carbonari"(rebels) of the Lombard-Veneto were celebrated. On March 17th, 1848 a insurrection that aimed to restore the Republic started, but the collapse of Venetian resistance in 1849 caused its end.
Victor Emmanuel II, King of Sardinia
According to Plombières agreements (July 21st, 1858), Venice should have ceded to Victor Emmanuel II, King of Sardinia, but Villafranca's preliminaries remained still subject to the Austrian crown untill the end of third Italian independence war, when it definatively ceded to Victor Emmanual II through Napoleon III (the treaty of Vienna - October 3rd, 1866). After the result of an official poll (October 22nd) Venice definitively joined the Kingdom of Italy.
Sources, bibliography and links:
 VVAA Enciclopedia Multimediale Rizzoli Larousse 2000 - Venezia
 John Julius Norwich History of Venice.
 Virtual History of Venice
 Veneto.Org - History
 Doge of Venice: History
 Venetian army in the XVII and XVIII centuries
 History of Murano glass
 Dogi of Venice
 The second Centennial of the end of the Serenissima
 Place and arts of Venice
 The Walls of Famagusta
 Famagosta (in Italian)
 W San Marco (in Italian)
 Italian Colony in Shanghai