[4] After service in both the Crimean War and the Indian Rebellion, Pakenham became Adjutant-General in India in November 1858.

He sat on the Conservative benches in the House of Lords and served as Under-Secretary of State for War from 1866 to 1868 under first the Earl of Derby and later Benjamin Disraeli.

In February 1870 he was voted chairman of the Central Protestant Defence Association which was established in response to the Irish Church Act 1869.

Lord Longford died in April 1887, aged 68, and was succeeded in the earldom by his second but eldest surviving son.

The Countess of Longford survived her husband by over thirty years and died in January 1918, aged 81.