Let me preface this by saying, I’m related to this buffoon. And if you say that this explains a lot, how dare you! * My 29th great-grandfather Henry I of England was the fourth son of great grand pappy William the Conqueror who most folks might remember from European history as the man who made Britain by stealing it away from those pesky Anglo-Saxons who were having a ball of a time with Vikings and their descendants (William among them) for the past 500 or so years.
If you’re wondering how a 4th son in the royal line managed to become King, that’d be because he had a few brothers to get through first. After the death of their father William, the title of the kingship passed to his third son, William II. His eldest son Robert Curthose was consistently a rebellious little prick and was originally supposed to be disinherited altogether, but William the Conqueror bequeathed him the Duchy of Normandy instead. It couldn’t pass to the second son Richard, who died in a hunting accident (This happens a lot. Maybe royalty shouldn’t hunt so much). And after everything had been divvied up, the will basically read “And none for Gretchen Weiners, bye!” and Henry I was left with nothing.
Meanwhile, Robert’s younger brothers, William and
Henry, had taken umbrage at his pretensions and at the rash
demands which he had made upon their father, and they were
strongly supporting the king against him. While in this frame
of mind they paid Robert a visit at his lodgings. Going into an
upper room, they began dicing ‘ as soldiers will ‘; and presently
doubtless after there had been drinking they started a row
and threw down water upon their host and his companions who
were on the floor below. Robert was not unnaturally enraged at
this insult, and with the support of his comrades he rushed in
upon the offenders, and a wild scuffle ensued, which was only
terminated by the timely arrival of the king, who, upon hearing
the clamor, came in haste from his lodgings and put a stop to the
quarrel by his royal presence. 
– Charles Wendell David, Robert Curthose: Duke of Normany on the prank that caused Robert’s first rebellion. Basically, he had a whole chamber pot of water dumped on his head by his younger brothers and wasn’t having any of it going forward.
Most likely fuming at the slight and ostensibly aware that his older brothers now had titles and armies over him, Henry I purchased a swath of land and began building himself forces to aid him in the coming wars against his brothers over the Kingship. Especially now that daddy was out of the way and unavailable to break-up their quarreling.
Years of infighting ensued until Henry I emerged victorious over his brothers. Henry I beat Robert in battle and kept him locked up in perpetuity and as for the short-lived King William II, he perished in another one of those “accidental” hunting incidents.
Once becoming king, Henry I spent most of his 35 year reign doing a bang up job at it, extending the reach of England, strengthening the government’s role in judiciary quibbles, and other awesome Kingly things. Except for the job of banging out an heir, apparently.
He did have one son, William the Aetheling and heir apparent, who was 17 and had been recently married, all the makings of a soon to be king naturally. Except, William and a large number of other nobles (around 200) decided to have a beach party rager not unlike an episode of Laguna Beach. Drunk out of their minds, they boarded The White Ship with the intent of crossing the English Channel, which the heavily inebriated captain suggested they could do well before the King did if they kicked it into high gear, and soon they were off sailing at high speed, having waved off priests who had intended to bless their safe passing because what could possibly go wrong on a pleasant night of drunken revelry such as this? The White Ship shattered upon a rock at the mouth of the harbor moments later, sinking Henry I’s future prospects with it. 
Henry I was kind of screwed at this point. He spent the next 10+ years trying to sire a new heir to no avail and plan out a contingency plan for his legacy (which, lol, this is British history we all know how well that will turn out). We can only imagine that the happiest times of his life then at this point, was probably related to dinner time. Medieval meals were pretty much only something to write home about if you were part of the aristocracy, and that’d be for either good or bad reasons. Because for every sugar sculpture, there was probably a batshit insane eel pie to go along with it. Which just so happened to be Henry I’s favorite dish. (WHY ARE MY BLOOD RELATIONS SO DISGUSTING)
On a November night in 1135, Henry I requested copious amounts of lamprey (eeeeel) pie, which is basically this disgusting sounding concoction of crusty baked eel fish things in a wine and spice syrup and excuse me, I’m gagging. Apparently, he ate so many of these nasty things that he fell incredibly ill. Within days, the king had succumbed to what the chronicles called a “surfeit of Lampreys”. Whatever the hell truly caused his death (some modern scholars contend the culprit to certainly be food poisoning at the least) , his corpse was so wretched following his death, that “the body was cut all over with knives and copiously sprinkled with salt and wrapped in oxhides to stop the strong pervasive stench, which was already causing the deaths of those who watched over it.”  Basically, for the love of all that is right and holy, do not put pineapple on your pizza and DO NOT EAT EEL PIES.
Cause of Death: BEING DISGUSTING
Fact check it, yo!
 David, C. W. (1920). Robert Curthose, duke of Normandy, by Charles Wendell David, .. Cambridge: Harvard University Press.
 Jones, D. (2014). The Plantagenets: the warrior kings and queens who made England. New York: Penguin Books.
 Crofton, I. (2014). A Curious History of Food and Drink. New York: Quercus.
* On my relation, I did some extensive genealogy research with Ancestry.com on my mother’s French side and was able to track our family back to the Plantagenets. I claim a slew of Viking kings, William the Conqueror, Henry I, and his daughter Empress Matilda as direct descendants. We start to deviate from there off with Matilda’s son William Plantagenet’s daughter marrying a Windsor. That line breaks somewhere in the 16th century and we start getting a bit more normal with each generation. Normal enough not to eat eel pies, anyway.