From the Wikipedia page 
Anne de Beauchamp, 16th Countess of Warwick (13 July 1426 – 20 September 1492) was the daughter of Richard de Beauchamp, 13th Earl of Warwick, and his second wife Isabel le Despenser. Isabel was a daughter of Thomas le Despenser (22 September 1373 – 13 January 1399/1400 and Constance of York. Anne was the mother of Anne Neville, Queen consort of England as the spouse of King Richard III.
Anne was born at Caversham Castle in Oxfordshire (now Berkshire). She became the wife of Richard Neville. Following the death of Anne's father, and subsequently that of her brother, Henry (who had been created a duke), and her niece Anne de Beauchamp, Neville inherited the title and the considerable estates of the Earl of Warwick through her.
However, this was contested by her three older half-sisters, children of her father's first marriage to Elizabeth, heiress of Berkeley. One of these, Eleanor, was married to Edmund Beaufort, Duke of Somerset (killed at the First Battle of St Albans in 1455). The litigation over the Warwick inheritance only fueled the enmity between this branch of the Nevilles and the Beauforts (who they were closely related to by common descent from John of Gaunt's third marriage). Law considered that Anne being a full-blooded aunt of the last countess was more eligible to inherit, regardless of the rule of primogeniture, which would have dictated the Beauchamp estates would pass to the eldest - Margaret Countess of Shrewsbury (d.1468). Alternatively, it could have followed the practice of equal division of lands between heiresses. Richard Neville was able to successfully keep the estates intact.
Her older daughter, [[Isabel Neville[[, married George, Duke of Clarence, the younger brother of King Edward IV of England. Her younger daughter, Anne Neville, was married to Edward of Westminster, the only son of King Henry VI. When Edward of Westminster was killed in the Battle of Tewkesbury, Anne was married to Richard, Duke of Gloucester, later King Richard III of England. Although their mother was still living, the husbands of the two Neville sisters fought over her inheritance, with Richard eventually coming out on top. However, the son of the Duke of Clarence inherited the earldom of Warwick from Neville. Anne died in obscurity, having survived both her daughters and the sons-in-law who had effectively disinherited her.