In 1899, Juno was equipped with wireless, and took part in the Summer Manoeuvres of that year. She relayed a message from Шаблон:HMS to Шаблон:HMS over a distance of 95 miles, the longest ship to ship transmission to date.[1]
The following year she served in the cruiser squadron. In May 1902 she was taken into Portsmouth for a refit,[3] and the following month Captain David Beatty was appointed in command.[4] She took part in the fleet review held at Spithead on 16 August 1902 for the coronation of King Edward VII,[5] and visited the Aegean Sea for combined manoeuvres with other ships of the Channel squadron and Mediterranean Fleet the following month.[6] After returning to Portsmouth in October,[7] she carried the Lord-Lieutenant of Ireland and Lady Dudley on a visit to Waterford on 29 October.[8] She was posted to the Mediterranean Fleet later that year, but Beatty paid her off not long after.
At the beginning of World War IJuno was assigned to the 11th Cruiser Squadron operating from Ireland.[9] In 1915 she was sent to the Persian Gulf and took part in an engagement at Bushire in July – August 1915 against Tangistani raids under Rais Ali Delvari.
Juno was returning to Queenstown, Ireland. Having received warning of submarine activity off Queenstown, the cruiser took evasive action and eventually returned to port. This warning was not extended to RMS Lusitania, which was sunk by a U-boat on Friday, 7 May 1915.