This was Frank Leslie, short, dark, bearded and already a household name – a highly successful publisher and pioneer in print technology. Soon Frank had abandoned his wife and moved in with the Squiers, a ménage à trois that lasted several years until Squiers, suffering from terminal syphilis, was move into a home. 

Escorted by the generous, free-spending Frank, Miriam travelled the world, dressed always in the height of fashion. Frank also put her in charge of one of his magazines, an ailing publication that she quickly turned into a success, largely by ignoring the horrors of the Civil War then raging, and giving women what she believed they wanted: fashion and frivolity. Circulation rose to 80,000 and Miriam’s confidence rose with it. 

By 1875, she was Mrs Frank Leslie, surviving headlines about his abandonment of his first wife and her own love affairs. Then Frank, who had over-expanded – in the Gilded Age, spending money was the only way to go – went bankrupt, clawed his way back, only to be diagnosed with throat cancer out of the blue. Within a week he was dead. 

Despite other dalliances, Miriam had loved him deeply. But she was not so stricken that she would allow his sons to overturn the will he had made in her favour. She won a bitter court case – and had her name legally changed to Frank Leslie – to secure her hold on the company. 

Her journalistic instinct was sure. When President Garfield was shot, at 9.30 a.m. on July 2 1881, within an hour Miriam had sent two artists to Washington to record the scene, her engravers (needed by all newspapers then for illustrations) worked through the night – and her paper was the only one to provide a pictorial record of the assassination attempt on the following Monday. When Garfield finally died, her reporters were not only at his bedside but in the cell of the murderer as well. Under her aegis, circulation soared from 33,000 to 200,000. 

There were lovers, there was a futile last husband whom she dumped, she wrote books, she gave hugely popular lecture tours, she lost and made another fortune, which she left to the suffrage cause. This is an extraordinary life, well told.

Diamonds and Deadlines by Betsy Prioleau is published by Abrams at £21.99. To order your copy for £16.99, call 0844 871 1514 or visit books.telegraph.co.uk