The martyrdom of Fatimah

Following the Farewell Pilgrimage, Muhammad summoned Fatimah and informed her that he would die soon, and also told her that she would be the next of his household to die. After Mohammad's subsequent passing away, Fatimah was grief-stricken and remained so until she herself died less than six months later. The Sunnis Muslims believe that Fatimah reconciled her differences with Abu-Bakr prior to her death, while the Shia Muslims believe that her anger with him remained. But the fact was that there is no any reconciliation between Fatimah and Abu-Bakr and that was one of the reason while her tomb still remain unknown up till our present day.

Why we saw the graves of the wives of the Prophet that dies years after the Prophet was known and seen and that of Fatimah that was martyred less than six months after the demise of the Prophet is not known?      
Shia and Sunni beliefs about her death diverge widely:
Sunni scholars say she died as a result of separation from her beloved father. The Sunni scholar Shaykh Muzaffer Ozak al-Jerrahi writes: 'After our Master had honored the world of the Hereafter, Fatima would neither eat nor drink and she forgot all laughter and joy. She had an apartment built for her in which she stayed by night and day, weeping her heart out for her beloved father.
She passed the time sobbing and sighing and nothing could take away her grief. As soon as she had done her household chores and taken care of her husband, 'Ali, and their sons, Hassan and Husain, she would continue weeping: "O my beloved father! To who have you left your Fatima?"
Shia maintains that Fatima died as a result of injuries sustained after her house was raided by Umar ibn al-Khattab who set fire to the house and stormed inside. His attack has cracked her rib-cage while she was pregnant. According to Shia tradition, Prophet Muhammad appeared in a dream and informed Fatimah that she would be passing away the next day. Fatimah informed her husband Ali of her impending death, and asked him not to allow the oppressors to be involved in her ceremonial prayers ''Salat al-Janazah|janazah'' (prayer performed in congregation after the death of a Muslim) or take part in the burial.
Some sources have stated that her two sons were the first family members to learn of her death and immediately proceeded to the mosque to inform their father. Upon hearing the news, Ali fell unconscious. After recovering he followed Fatima's wishes and performed the (janazah). He buried her during the night on 3rd Jumada al-Thani, and also makes three false graves to ensure her real grave could not be identified. With him were his family and a few of his close companions.
Shia, especially the Iranians holds ceremonies every year for 20 days between Jumada al-awwal and Jumada al-Thani to commemorate the anniversary of the martyrdom of Fatimah. Mourners march in procession through the streets to reaffirm their allegiance to the ideals of Fatima in particular and the AhlulBayt in general.