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| YEAR | DATE | EVENT | HEAD OF STATE |
| 770 | Mark of H.R.E. | ||
| 1198 | Earldom - dinasty Este | count Azzo VI sire of Ferrara | |
| 1212 | count Aldobrandino sire of Ferrara | ||
| 1215 | count Azzo VII sire of Ferrara | ||
| 1229 | Free Common | ||
| 1331 | Lordship - dinasty MonteVerde | sire Mercenario | |
| 1340 | sire Rinaldo (I) | ||
| 1348 | dinasty da Mogliano | sire Gentile | |
| 1360 | dinasty Visconti | sire Giovanni | |
| 1366 | sire x | ||
| 1376 | dinasty Monteverde | sire Rinaldo (II) | |
| 1379 | sire x | ||
| 1393 | dinasty Aceti | sire Antonio | |
| 1397 | dinasty Tomacelli | sire Andrea | |
| 1405 | dinasty Migliorati | sire Lodovico | |
| 1408 | papal vicaire Lodovico | ||
| 1428 | sire Fermino | ||
| 1428 | december | Church Territory | |
| 1433 | Lordship - dinasty Sforza | sire Francesco | |
| 1447 | Church Territory | ||
| 1502 | Lordship - dinasty Eufredducci | sire Oliverotto | |
| 1502 | dinasty Borgia | sire Cesare | |
| 1503 | Church Territory | ||
| 1520 | Union to Church State |