It is unknown how the conflict between dragons and humans began, but it is possible that 300 years before the events of the first film, a Viking possibly, Bork the Bold accidentally started the war with the dragons. ("Book of Dragons (Short)")
During this time, there was a gathering of viking chieftains on Berk to discuss the war with the dragons. It was during this gathering that a man, Drago Bludvist, stepped forth. Bludvist claimed he could control the dragons and end the war if the chiefs bowed down and followed. Stoick and the other chiefs laughed at this until Bludvist left. The chiefs then came under attack by armored dragons that burned the hall to the ground. Only Stoick survived the attack.(How to Train Your Dragon 2)
During this time, Stoick's wife, Valka, tried to urge both Stoick and their tribe to end the war with the dragons to no avail. When dragons launched another raid, Valka then rushed into their home to protect her newborn son, Hiccup, from a dragon. However, seeing no malice in the dragon, she could not kill the dragon. Stoick then rushed into to protect both Valka and his son. Unfortunately, Valka was then taken by the dragon and many believed she had eaten and killed by the dragons.(How to Train Your Dragon 2) Stoick then searched for her for days but was forced to give it up.("Imperfect Harmony")
List of Events
The Last Raid
15 years later, Stoick and the rest of the tribe continued to fight the dragons. During this raid, the dragons took a substantial amount of Berk’s farm animals back to their island.("How to Train Your Dragon")
The first search for Dragon Island
For three hundred years, dragons lived on the island and made raids on Viking islands such as Berk. On the island in the mountain, the Red Death demanded all the dragons to give it all their food or he would eat them. Hairy Hooligan chief Stoick the Vast and his Vikings attempted to find the island before the ice sets, to no avail. The Island was then discovered by Stoick's son Hiccup, and Astrid Hofferson when Hiccup helped and trained the Night Fury Toothless.
The Incident at the kill ring
The final test begins. Instead of killing it, however, Hiccup tries to tame it to prove the dragons aren't dangerous creatures. His father's insistence on stopping the test makes the Monstrous Nightmare revert into its regular state into attacking Hiccup. Toothless hears his human friend's cries of fear and help from the cove and rushes to save him, climbing out of the cove by himself and running through the forest. Astrid enters the battle arena in an attempt to save Hiccup but fails to fight off the Monstrous Nightmare. Stoick helps Astrid get out of the arena but Hiccup is stopped short when the dragon blocks him from escaping. Toothless arrives in the nick of time and saves Hiccup by fighting away the Monstrous Nightmare.
The second search for Dragon Island
Stoick then led the tribe using Toothless to find their way through the fog bank. Once there, they attacked the dragons, scaring them away until the Red Death burst out of the mountain, destroying the ships.
The Battle of the Red Death
|— Stoick & Hiccup during the battle|
The Vikings reach the Nest using a shackled Toothless as a guide, then use catapults to blow a hole in the Nest's lower base. Upon doing so, the dragons flee from the enraged Red Death, causing it to break through the side and attack the Vikings, setting all of the longboats on fire, including the one Toothless is chained up on, leaving them with no escape. Stoick realizes the scale of the fight Hiccup tried to tell him and curses himself as a fool. He, along with Gobber, decide to sacrifice themselves to let the others escape. However, both them and the Red Death are halted in their efforts when Hiccup and his friends arrive on dragon's back and shoot at the back of the Red Death's head. Hiccup instructs Snotlout, (riding the Monstrous Nightmare), and Fishlegs, (riding the Gronckle), to go to the Red Death's blind spot and make noise to keep it confused while Ruffnut and Tuffnut, (riding the Hideous Zippleback), exhaust the Red Death's shot limit and Astrid, (riding the Deadly Nadder), drops off Hiccup so he can free Toothless. However it turns out Fishlegs and Snotlout can't find a blind spot due to multiple eyes on the side of its face but they continue to bash the shields, this works on the Red Death but also works on Fishlegs' Gronckle and Snotlout's Monstrous Nightmare. The Nightmare flings Snotlout onto the head of the Red Death while the Gronckle drops altitude. Fishlegs, before crashing, throws Snotlout his hammer which Snotlout uses to hit the Red Death's eyes so it doesn't step on Fishlegs. In the Red Death's thrashing about in steps on the boat Hiccup and Toothless are on and Toothless sinks a few feet below water. Hiccup still tries to save him but passes out from lack of air. Stoick, amazed at what Hiccup and his friends did, dives down and saves them both. After apologizing to his son, he tells him he doesn't have to face the dragon, but with a smile, Hiccup replies, "We're Vikings: it's an occupational hazard", something Stoick said early in the movie. Telling Hiccup he's proud to have him as his son, Stoick watches as Hiccup climbs aboard Toothless and heads toward the Red Death. Astrid instructs the twins to get Snotlout off the Red Death's head which they do. However, Astrid is almost sucked in and eaten by the Red Death until Toothless and Hiccup stop it with a plasma blast. Astrid falls off her Nadder due to the force of the plasma explosion but Toothless catches her. After dropping her off, Astrid silently says "go".
Hiccup angers the Red Death into following him with Toothless using a powerful plasma blast. After leading it up high enough into the dark clouds, they hide among them and while diving past at high speed, repeatedly blasting hole after hole into the Red Death's wings. In pain and anger, the giant blasts a long stream of fire all around it, setting Toothless' prosthetic tail-fin alight when the Night Fury can't avoid the flames. Knowing they have little time left, Hiccup dives nearly straight down, the Red Death in hot pursuit. When he hears the sound of the Red Death heating its gasses to fry them, he waits for the last possible moment, then shouts to Toothless; Toothless spins around and fires a plasma blast directly into the Red Death's mouth, prematurely igniting the gas and setting its insides on fire. Toothless twists away and slips past its head, as it realizes its about to hit the ground. However, when it spreads its wings to stop itself, all the holes in its wings tear into even bigger holes, rendering its wings useless.
As the huge dragon crashes at full speed and explodes, Hiccup is knocked off unconscious when Toothless is unable to turn away from hitting the Red Death's tail after his prosthetic fin burned. Seeing Hiccup fall towards the flames beneath, Toothless dives into the inferno of the Red Death's exploding body to save him. After the smoke from the battle clears, it is shown Toothless survived, with his prosthetic fin destroyed and his saddle empty and burned. Everyone believes Hiccup was killed in the explosion, reducing Stoick to tears. He apologizes, saying how sorry he was for not listening to his son. Toothless sees this and unfurls his wrapped up wings, revealing he has an unconscious Hiccup clutched to his body: his fire-proof dragonhide saved Hiccup's life.
In How to Train Your Dragon, following the victory over the Red Death, Stoick allowed the dragons to move in with them on Berk. During this time, Hiccup received a metal leg from Gobber. With Toothless at his side, Hiccup and the other teens rode their dragons. In "How to Start a Dragon Academy, they started the Dragon Training Academy to train both riders and dragons. News of Hiccup's victory reached the other tribes such as the Outcasts ("Alvin and the Outcasts") and the Berserkers.("Twinsanity")