On the morning of 31 January 1703 (Western Calendar), the end of a drama started 14 months before played out (Author's Note: This is largely pulled from last year's post).
The Ako Icident (as it is formerly referred to in the history of the time) started in 1701, when a daimyo, Asano Naganori, was forced to commit seppuku (ritual suicide, literally "cutting of the stomach") after he attacked a high court official, Kira Yoshinaka, in the palace of the Shogun. To draw a sword inside the castle was strictly forbidden, to attack even more so. Asano had felt deeply insulted as Kira has degraded and insulted him in the course of instructing him in court etiquette (popular rumor was it was because Kira was hoping for a bribe).
(The Head Washing well, where the 47 Ronin washed the head of Kira Yoshinaka off before presenting it at the tomb of their lord).
After his suicide, the Shogunate demanded the Asano family's domain of Ako be surrendered (along with its castle), its goods confiscated, and its samurai made ronin (literally "A man of the waves" or a masterless samurai, which did not find a place in the Tokugawa's Neo-Confucian social structure of warrior, merchant, farmer, and craftsman).
(The tomb of Oishi Kuranosuke, leader of the 47 Ronin)
Oisihi, having been notified of the impending forfeiture, first moved the remaining Asano family members and then, against the arguments of some of his clan, formally surrendered the castle and its domain. He requested to re-establish the house of Asano but failed.
In the meantime, he had a second plan.
(Tombs of Yohida Chuzaemon and Hara Soemon, ages 63 and 56 [respectively] at the time of the Ako Incident)
(The tomb of Maze Kydayu, age 63 at the time of the Ako incident)
Oishi began reaching out to former retainers of the Asano with a plan: To take revenge on Lord Kira by his assassination. This would be difficult, as Kira was on the watch and carefully monitoring the movements of Oishi and many of the former Asano samurai.
(The tomb of Hazama Kihyoe, age 69 at the time of the Ako incident.)
And so Oishi hatched a plot. Reaching out to key retainers, he began to construct a plan whereby he and the retainers would ambush Kira. This would have to be completely in secret and could not be done while Kira suspected a thing.
(The tomb of Horibe Yahyoe, age 77 at the time of the Ako Incident, proving you are never too old to act.)
Not only would the men have to gather; they would have to get arms and armor without raising suspicion and assemble at a given time when Kira was in a location and no longer suspicious.
The execution of the plan took 14 months. During that time, Kira's agents tracked Oishi in Kyoto. What they saw was a man who apparently had given himself over entirely to pleasure, visiting the pleasure quarters and drinking and carrying on with women. All the time in the background, the team continued to work to gather arms and manufacture armor in secret and remain in contact.
Finally, Kira's agents gave up. Oishi had turned into a wastrel and his men the same. There was no threat.
On 31 January 1703, Oishi and 46 other ronin, all former retainers of the Asano, stormed Kira's mansion in Edo (now Tokyo). Splitting into two groups (Kuranosuke led one and his son, 15 year old Chikara, led the other,) they captured the porters lodge and opened the gate.
Prior to the start of the attack, Oishi emphasized to his men that their target was Lord Kira: women, children, and non-combatants were to be spared. He also sent messengers to Kira's neighbors, notifying them of the attack and that they were in no danger. And at the formal initiation of the attack, one of the 47 Ronin climbed to the roof and announced the attack to the neighborhood and that this was an act of revenge.
The attack went on through the night. The 47 stormed the house and began searching for Kira. Kira's retainers, when they realized they were losing, attempted to go for aid but were cut down by Oshi's bowmen stationed on the walls. 16 retainers were killed and 22 injured, but Kira could not be found.
Finally, in a shed for storing charcoal and firewood, a man was found. Refusing to give his name, he was examined. His head bore a scar, put there by the sword of Asano. Lord Kira had been found.
Oishi addressed Kira as a retainer would based on Kira's rank, explaining why they had come and offering Kira the chance to commit seppuku and retain his honor; Oishi would act as his kaishakuin (second) and behead him to prevent suffering. Kira was shaken and trembling; finally, seeing there was no change, Oishi cut off Kira's head with a dagger.
Extinguishing all lamps to prevent any risk of fire, The 47 Ronin sent one man, Terasaka Kiechiemon, to the Asano domain to announce the deed. The now 46 Ronin began a walking retreat to Sengaku-ji, a temple favored by the Asano's. The story spread quickly and as they marched along, they were feted and offered refreshments by passers-by.
(The tomb of Oishi Chikara, age 16 at time of death. He was Oishi Kuranosuke's son.)
Upon arriving at Sengaku-ji, they washed Kira's head in a nearby well (seen above) and presented it and the dagger that had cut it off on the grave of Lord Asano. Praying at the temple and giving their remaining funds to the Abbott, they surrendered to the Shogunal authorities.
The Shogunal government was in a bit of a pickle. Lord Kira was not a popular man, and at the time the decision against Lord Asano had been wildly unpopular. Also, The 47 Ronin had demonstrated a retainer's loyalty to one's lord, something that the Shogunal government was effectively built on. To decry that would be to decry the very existence of the Shogunate.
At the same time, the government could not support acts of revenge like this - there was a process for seeking revenge, but it was a defined process and included a formal declaration of the act of seeking revenge. The 47 Ronin had done none of this.

The government came to the following decision: The 46 Ronin, who had been placed in the custody of four daimyo, were to commit seppuku, allowing them to die as warriors and retain their honor. No revenge could be sought by Kira's family. The matter was closed.
The Ronin had always planned this as a possible outcome. And so, on 20 March 1703, the 46 committed seppuku. Their remains, along with the remains of Lord Asano and his wife Yozen-in (Buddhist name), were buried at Sengaku-ji.

One may note only 46 died. The 47th, Terasaka Kiechiemon, who had been sent to the Asano domain to declare the revenge, was pardoned by the Shogunate. Accounts vary of why he was pardoned: some say it was because of his youth, others that it was "plot" by Oishi and the others by clearly stating he as not part of the action to allow his survival. He lived until 1747 and died at the age of 87, when he was then buried with his comrades.
Another odd note: There are 48 graves for the Ronin present. Added in their number is Kayano Shigezane, a retainer who was forced to commit seppuku when a family member disapproved of his taking part in the act.
A final note: The Asano were restored to their status, but not as the Lords of Ako domain.
A festival for The 47 Ronin is celebrated at the temple on 14 December.

One climbs the stairs above, where a monk and/or a volunteer will take 300 Yen and offer you lighted incense sticks, which are placed on the stone alters in front of each grave.
This was my third time in Sengaku-ji. It is a humbling and haunting experience, made more so by the fact that this events really happened.
(The nun who originally cared for the graves of the 47 Ronin stated she had received this tree from Asano Naganori. That would make it well over 300 years old.)
(The Chizome, or Blood stained stone. It is said that when Asano Naganori committed seppuku in the garden of Tamura Ukyodayu, his blood gushed out on this stone, which was relocated to the temple grounds).
Further information: If one wants to learn more, the Wikipedia link above is a great start. Do not - and I mean DO NOT (Update 2025: By all means DO NOT) - by any means watch the more recent movie starring Keanu Reeves (whom otherwise I enjoy as an actor) - it has almost nothing to do with the actual story except there may be a revenge and 47 Ronin may be involved. If you have a long period of time, there was a 1941 movie produced which, while not having the fighting, is probably more true to the actual events (located at archive.org). There have been more recent (1950's to 1970's) adaptations. Perhaps unsurprisingly, it instantly became a classic in the samurai culture and remains so to this day.
For written works, I cannot recommend highly enough Donald Keene's translation of Kandehon Chushingura (more colloquially known as "The Chushingura)". Originally developed as a bunraku (puppet play), it had to recast the events to an earlier period due to Shogunal censorship but retains the spirit of the events (especially Oishi's deception).
The 47 Ronin on their way to Sengaku-ji, stopped by locals for refreshment (
Source)