What are the facts behind the Battle of the Camel and the allegations against Hazrat Umar (ra)?

Hazrat Amirul Momineen, Khalifatul Masih V^aa was asked about the causes and the truth behind the Battle of the Camel, as some people allege that Hazrat Umar^ra had mercilessly beaten Hazrat Fatima^ra, due to which Hazrat Fatima^ra lost her pregnancy. 

Hazrat Amirul Momineen^aa, in a letter dated 21 November 2019, gave the following reply: 

“The allegation against Hazrat Umar^ra regarding Hazrat Fatima^ra is utterly absurd, unfair and contrary to actual events and facts. Hazrat Fatima^ra was only alive for a few months after the demise of the Holy Prophet^sa. She spent most of that time in illness. 

“Moreover, Hazrat Fatima^ra was the daughter of the Holy Prophet^sa. How could Hazrat Umar^ra ever treat her in such a cruel manner? Hazrat Umar^ra would show immense love to even those people who were merely associated with the Holy Prophet^sa even if they were not his physical progeny. 

“Hence, on one occasion, Hazrat Umar’s^ra son, Hazrat Abdullah^ra, asked him as to why he had allocated less allowance for him than Usama^ra ibn Zaid. Hazrat Umar^ra replied, ‘Usama was more beloved to the Holy Prophet^sa than you and his father (Hazrat Zaid^ra ibn Harithah) was dearer to him than your father (i.e. Hazrat Umar^ra). That is why I have given more allowance to him.’

“Thus, to allege that the person who preferred the son of the Holy Prophet’s^sa servant over his own son so much and had maltreated the physical progeny of the Holy Prophet^sa, cannot be correct by any measure. This is a completely false allegation against Hazrat Umar^ra by his enemies. 

“As far as the reality of the Battle of the Camel is concerned, there is no doubt that this war was fought between two groups of Muslims; they were the armies of Hazrat Ali^ra and Hazrat Aisha^ra. No other battle that Muslims fought was as bloody as this one. Many Muslims, including great generals and men of great valour, were killed. However, the culprits behind this entire episode were the same seditious insurrectionists who had occupied Medina after killing Hazrat Uthman^ra. This war was also provoked by those miscreants by creating a misunderstanding between the two Muslim groups and by instigating many mischievous acts themselves. 

“Hazrat Musleh-e-Maud^ra has discussed this subject at great length in Waqiat-e-Khilafat-e-Alawi. Read that too.”