Fadak (فدك) was a garden oasis in Khaybar, a tract of land in northern Arabia; it is now part of Saudi Arabia. Situated approximately 140 km (87 mi) from Medina, Fadak was known for its water wells, dates, and handicrafts. When the Muslims defeated the people of Khaybar at the Battle of Khaybar; the oasis of Fadak was part of the bounty given to the Prophet Muhammad, who gifted it to his daughter, Fatimah.
Hazrat Mohsin (AS) was martyred when they attacked the house of Fatima (AS) . This tragedy on Ahlul Bayt (AS) happened immediately after the Saqeefah conspiracy as Saqeefah people wanted to forcibly take allegiance from Ali (AS).
Confiscation of Fadak from its real owner Fatimah (AS) took place when they started their government.
Imam Ali (AS) did not use his authority as the head of the state for his own benefit or the benefit of his family, that is why he did not take back Fadak during his government. It is narrated that he was asked: Why don't you take back Fadak? He replied: The oppressor and the victim have left this life and Allah has given the victim her reward and the oppressor his punishment, so, I do not want to take it back.
Imam Ali (AS) spent the income of Fadak on the poor and needy despite of the fact that Fadak was the property of the inheritors of Fatimah (AS). Imam Musa Al-Kadhim (AS) was asked same question about Imam Ali (AS) not taking back Fadak for him and his children from Fatimah? He replied: We are Ahlul Bayt, take the right of people and give it to them, and do not take our own right and leave it to the Justice of Allah (SWT).
Keep in mind that one of the main objections of Muslims on Uthman ibn Affan that he used to give state properties to his relatives. If Imam Ali (AS) took Fadak , which was under the state properties since 25 years, and gave it to his children from Fatimah, the Munafiqeen will say that he is doing like Uthman. After all, he will give the income of it to the poor and needy, whether it is under his children ownership or state's ownership. He did not take it back during his government and left his right and his children's rights to Allah (SWT).
There are many books written on this important subject but not all of them are translated to English. There is a book available on line which was published by Amazon: THE TRAGEDY OF FATIMA DAUGHTER OF THE PROPHET MUHAMMAD, by Allama Sayyid Murtada Al-Amili, translated by Yasin Al-Jibouri.
Also it might be useful for you to see this link
Lady Fatima (AS) was gifted the property of Fadak from her father the Prophet Muhammad (SAWA) by order from Allah (SWT) to make her financially independent to help the believers who are in need. All the wealth and properties of Ahlul Bayt (AS) used to be spent to help the believers in need.
The tyrants who illegally confiscated Fadak from Fatima (AS) did not want her to be able to do that. They wanted to make her look financially weak and unable to help.
The crime of confiscating Fadak from Lady Fatima (AS) has got many dangerous sides including denying her statements and the statements of Ameerul Mo'mineen Ali (AS) and Hasan (AS) and Husain (AS) and fabricating a false narration on the Prophet (SAWA) which was never said by him.
The tragedy of Lady Fatimah (SA) and her sufferings from Abu Bakr is mentioned in
hundreds of Sunni books and thousands of Shia books. I will mention
only the book of Bukhari being the most important book of Hadeeth among
our Sunni brothers. In the book of Bukhari, Hadeeth number 4240, it is
mentioned that Fatimah asked Abu Bakr to give her her right from what
the Holy Prophet (SAWA) left. Abu Bakr refused to give anything of
that to Fatimah (SA) so she became angry with Abu Bakr and boycotted
him and did not talk to him till she died. She remained alive after
her father for 6 months and she never spoke to Abu Bakr. This is in
the book of Bukhari itself.
It is important to know that Bukhari himself narrated a Hadeeth from
the Holy Prophet (SAWA) that Fatimah (SA) is part of me, anyone who
makes her angry makes me angry – this is in Bukhari, volume 4, page
210 in the Arabic edition.
Based on the information that I have come across, the wives of the Prophet (s) did not receive an inheritance from his estate, but rather were given a 'provision' or stipend. This was either left for them in the lifetime of the Prophet (s) or was given by Abu Bakr as the first defacto caliph.
So were the wives not entitled to any inheritance? There is an interesting narration in the Mu'jam al-Buldan of Yaqut al-Hamawi that after the demise of the Prophet (s) the wives considered sending 'Uthman (presumably bin 'Affan) to Abu Bakr as their representative to demand their eighth share. But 'Aisha, the daughter of Abu Bakr and one of the wives of the Prophet (s), opposed it and all the wives withdrew from such a demand.
This is important because had the wives been entertained in their claim for inheritance, then Lady Fatima's (a) claim to Fadak could not have been refuted on the grounds that the Prophets do not leave heirs as was claimed by the first caliph Abu Bakr.
Fadak, in any case, was a lifetime gift that the Prophet (s) had made to Fatima (a). That estate was not handed over to her by Abu Bakr despite her claims to it. This is widely documented in the hadith and historical sources.
For more details on the estate of Fadak and the politics that was at play behind it being withheld from Fatima (a) please refer to: