| YEAR | DATE | EVENT | HEAD OF STATE |
| 1261 | Duchy of Saxe-Lauenburg - dinasty Ascani | electoral prince and duke John I | |
| 1286 | duke John II | ||
| 1322 | duke Erik I | ||
| 1359 | duke Alberto V | ||
| 1367 | duke Erik III | ||
| 1401 | duke Erik IV | ||
| 1411 | duke Erik V | ||
| 1435 | duke Bernardo II | ||
| 1463 | duke John II | ||
| 1505 | duke Magnus I | ||
| 1543 | duke Francesco I | ||
| 1581 | duke Magnus II | ||
| 1588 | duke Francesco II | ||
| 1619 | duke Augusto | ||
| 1656 | duke Giulio Enrico | ||
| 1665 | duke Francesco Ermanno | ||
| 1666 | Duchy of Lauenburg | duke Giulio Francesco | |
| 1689 | dinasty Brunswick-Este | duke Georg Wilhelm duke of Kalenberg | |
| 1705 | 28 august | duke George I King of Great Britain | |
| 1727 | Duchy of King of Great Britain | ||
| 1810 | French Occupation | ||
| 1815 | Duchy of King of Danmark | ||
| 1864 | Duchy under Prussian administration | ||
| 1918 | Union with Schleswig-Holstein |