María Josefa de las Mercedes Lasala Fernández Larrazabal was born in Buenos Aires on 23 September 1764 and baptised two days later.

[6] On 13 April 1782 Mercedes de Lasala married Miguel Fermín Mariano Riglos San Martín (12 October 1754 – 16 May 1808) in Buenos Aires.

[7] Mercedes de Riglos was among the well-to-do women of Buenos Aires who held weekly social gatherings that were open to anyone introduced by a friend.

[10] It was at meetings at her house and those of other society women such as Mariquita Sánchez de Thompson and Flora Azcuénaga that the discussions were held which led up to the May Revolution, the first stage in the struggle for Argentine independence from Spain.

Public events were discussed good humouredly, almost philosophically; and as the three ladies in question were all favourable to European alliances, their houses were the constant resort of both English and French naval commanders, consuls-general and other foreign envoys and diplomatists.

[1] Doña Ana Riglos, a widow, was a nice and intelligent old lady; vivacious, well bred, with a tinge of aristocratic etiquette of the old school, she was yet at home with every body, and her parties were of the pleasantest I knew.

A mighty favourite (and deservedly so) he was of his mother and sister, and still more of his aunt, Doña Eusebia de la Sala[b]—perhaps the best natured, kindest, and frankest woman in Buenos Ayres.

She was popular with English naval officers because of her patience in correcting their linguistic errors and her willingness to defend them against criticism for their sad figure in the local dances.

[3] Doña Melchora de Sarratea, queen of fashion and of the Buenos Aires salons, was so well aware of public and private affairs that she was held to be an enthusiastic supporter of Whig (liberal) principles.

She had great wealth and collected outstanding personalities and also exquisite and curious products of European art and industry such as porcelains, engravings and clocks.