In 1127 [his father] Henry "Proud" Welf X Duke Bavaria (age 19) and [his mother] Gertrude Süpplingenburg Duchess Bavaria were married. She by marriage Duchess Bavaria. He the son of [his grandfather] Henry "Black" Welf IX Duke Bavaria and [his grandmother] Wulfhilde of Saxony Duchess Bavaria.

In 1129 Henry "Lion" Welf XII Duke Saxony III Duke Bavaria was born to Henry "Proud" Welf X Duke Bavaria (age 21) and Gertrude Süpplingenburg Duchess Bavaria at Brunswick [Map].

On 20 Oct 1139 [his father] Henry "Proud" Welf X Duke Bavaria (age 31) died.

In 1142 Henry "Lion" Welf XII Duke Saxony III Duke Bavaria (age 13) was appointed XII Duke Saxony. [his future wife] Clementia Zähringen Duchess Saxony Duchess Bavaria by marriage Duchess Saxony.

In 1147 Henry "Lion" Welf XII Duke Saxony III Duke Bavaria (age 18) and Clementia Zähringen Duchess Saxony Duchess Bavaria were married. They divorceddd in 1162. She the daughter of Conrad Zähringen 1st Duke Zähringen. He the son of Henry "Proud" Welf X Duke Bavaria and Gertrude Süpplingenburg Duchess Bavaria.

In 1155 [his daughter] Gertrude Welf was born to Henry "Lion" Welf XII Duke Saxony III Duke Bavaria (age 26) and [his wife] Clementia Zähringen Duchess Saxony Duchess Bavaria.

In 1156 Henry "Lion" Welf XII Duke Saxony III Duke Bavaria (age 27) was appointed III Duke Bavaria. [his wife] Clementia Zähringen Duchess Saxony Duchess Bavaria by marriage Duchess Bavaria.

Around 1157 [his daughter] Richenza Welf was born to Henry "Lion" Welf XII Duke Saxony III Duke Bavaria (age 28) and [his wife] Clementia Zähringen Duchess Saxony Duchess Bavaria.

On 01 Feb 1168 Henry "Lion" Welf XII Duke Saxony III Duke Bavaria (age 39) and Matilda Plantagenet Duchess Saxony (age 12) were married. She by marriage Duchess Bavaria, Duchess Saxony. The difference in their ages was 27 years. She the daughter of King Henry "Curtmantle" II of England (age 34) and Eleanor of Aquitaine Queen Consort Franks and England (age 46). He the son of Henry "Proud" Welf X Duke Bavaria and Gertrude Süpplingenburg Duchess Bavaria.

In 1172 [his daughter] Matilda Welf Countess Perche was born to Henry "Lion" Welf XII Duke Saxony III Duke Bavaria (age 43) and [his wife] Matilda Plantagenet Duchess Saxony (age 15). She a granddaughter of King Henry "Curtmantle" II of England.

Around 1173 [his son] Henry Welf V Count Palatine of the Rhine was born to Henry "Lion" Welf XII Duke Saxony III Duke Bavaria (age 44) and [his wife] Matilda Plantagenet Duchess Saxony (age 16). He a grandson of King Henry "Curtmantle" II of England.

Around 1174 [his son] Lothar Welf was born to Henry "Lion" Welf XII Duke Saxony III Duke Bavaria (age 45) and [his wife] Matilda Plantagenet Duchess Saxony (age 17). He a grandson of King Henry "Curtmantle" II of England.

Around 1175 [his son] Otto Welf IV Holy Roman Emperor was born to Henry "Lion" Welf XII Duke Saxony III Duke Bavaria (age 46) and [his wife] Matilda Plantagenet Duchess Saxony (age 18). He a grandson of King Henry "Curtmantle" II of England.

In Feb 1177 William "Good" II King Sicily (age 22) and [his sister-in-law] Joan Plantagenet Queen Consort Sicily (age 11) were married. She by marriage Queen Sicily. She the daughter of [his father-in-law] King Henry "Curtmantle" II of England (age 43) and [his mother-in-law] Eleanor of Aquitaine Queen Consort Franks and England (age 55).

Before 17 Sep 1177 Alfonso VIII King Castile (age 21) and [his sister-in-law] Eleanor Plantagenet Queen Consort Castile (age 15) were married. She by marriage Queen Consort Castile. She the daughter of [his father-in-law] King Henry "Curtmantle" II of England (age 44) and [his mother-in-law] Eleanor of Aquitaine Queen Consort Franks and England (age 55). He the son of Sancho III King Castile and Blanche Ramirez Queen Consort Castile. They were half fourth cousins.

In Jul 1181 [his brother-in-law] Geoffrey Plantagenet 2nd Duke Brittany (age 22) and Constance Penthièvre Duchess Brittany (age 20) were married. She by marriage Duchess Brittany. He by marriage Duke Brittany. She the daughter of Conan "The Young" Penthièvre IV Duke Brittany and Margaret Dunkeld Duchess Brittany (age 36). He the son of [his father-in-law] King Henry "Curtmantle" II of England (age 48) and [his mother-in-law] Eleanor of Aquitaine Queen Consort Franks and England (age 59). They were half second cousin once removed. She a great x 2 granddaughter of King Henry I "Beauclerc" England.

On 11 Apr 1184 [his son] William of Winchester Welf was born to Henry "Lion" Welf XII Duke Saxony III Duke Bavaria (age 55) and [his wife] Matilda Plantagenet Duchess Saxony (age 28) in Winchester, Hampshire [Map] during his father's exile. He a grandson of King Henry "Curtmantle" II of England.

On 19 Aug 1186 [his brother-in-law] Geoffrey Plantagenet 2nd Duke Brittany (age 27) died at Paris [Map].

In 1189 [his son-in-law] Geoffrey Chateaudun III Count Perche and [his daughter] Matilda Welf Countess Perche (age 17) were married at Rouen, France [Map]. She by marriage Countess Perche. She the daughter of Henry "Lion" Welf XII Duke Saxony III Duke Bavaria (age 60) and [his wife] Matilda Plantagenet Duchess Saxony (age 32). He the son of Routrou Chateaudun IV Count Perche (age 54) and Matilda Blois Countess Perche. They were third cousin once removed. He a great x 2 grandson of King William "Conqueror" I of England. She a granddaughter of King Henry "Curtmantle" II of England.

On 28 Jun 1189 [his wife] Matilda Plantagenet Duchess Saxony (age 33) died. She was buried at Brunswick Cathedral [Map].

In 1193 [his son] Henry Welf V Count Palatine of the Rhine (age 20) and [his daughter-in-law] Agnes Palatine of the Rhine were married. She by marriage Countess Palatine of the Rhine. He the son of Henry "Lion" Welf XII Duke Saxony III Duke Bavaria (age 64) and [his former wife] Matilda Plantagenet Duchess Saxony. He a grandson of King Henry "Curtmantle" II of England.

On 06 Aug 1195 Henry "Lion" Welf XII Duke Saxony III Duke Bavaria (age 66) died at Ravensburg.

[his son] Henry Welf was born to Henry "Lion" Welf XII Duke Saxony III Duke Bavaria and Clementia Zähringen Duchess Saxony Duchess Bavaria.