In the 13th century Lincoln was the largest diocese in England it's inhabitants made up one fifth of the entire population of the country and it was here in 1235 that he was appointed bishop.
Before his appointment however, Grosseteste had written several important texts on the subjects of creation and redemption. He was also a scientist, and is seen as having a major role in the development of western scientific tradition. His work On Light or the Beginning of the Forms - which was written around 1220, includes his thoughts on cosmogony, he even wrote of the physics of rainbows.
Grosseteste was intelligent and influential and according to English chronicler Matthew Paris he regarded himself as personally responsible for the spiritual welfare of every individual in the diocese.
Almost as soon as he had settled into his position as Bishop of Lincoln he quarreled with the clergy, he denounced the pope and the Lincoln's cardinals to their faces stating that they ‘acted contrary to Christ’. Grosseteste was uncompromising and forthright and this lead to the Pope giving him up as unmanageable. He also had a sharp tongue and didn't mince his words, he once said to Henry de Montfort, the eldest son of the more famous Simon.
"My beloved child, both you and your father will meet your deaths on one day, and by one kind of death, but it will be in the name of justice and truth."
Grosseteste was right for on the 14th of May 1264 at the Battle of Lewes, both Henry and his father Simon died grisly deaths.
Of Henry de Montfort's death, the
'first born son and heir, in full view of his father, perished, split by a sword.
and Simon himself:
"the head was severed from his body, and his testicles cut off and hung on either side of his nose"