The outgoing deputy head of the Royal Navy has warned – "if we don't transform we will fail and we will lose".
In an unprecedented move, departing Second Sea Lord Vice Admiral Nick Hine posted his exit letter, addressed to all members of the Royal Navy, Royal Marines and civil servants, on Twitter.
In it, he said he "would do it all over again; the good the bad and the indifferent", but stressed that change must happen within the service.
In part of his letter, he urged "those who would have preferred to have the brakes on, the pedants and naysayers" to "remain critical (always)".
He continued: "But please understand that the need for, and the value of change, is not a fantasy – if we don't transform, we will fail and we will lose. It is that simple".
The departing Deputy Chief of Naval Staff said his "bugbear" was that "our great Navy has lost its ambition".
VAdm Hine said the last two-and-a-half years had been "uncomfortable, uncertain and exciting in equal measure".
He later wrote: "I am saddened that I have not been able to realise the level of ambition that I know is possible and needed."
VAdm Hine, who served on tours of Iraq, Kosovo and Northern Ireland, said it had been "an honour and a privilege to serve", and urged members of the service to "be ever braver" and "be better than yesterday".
VAdm Hine handed over the role of Second Sea Lord to Vice Admiral Martin Connell on Wednesday.
VAdm Connell was commissioned into the Royal Navy in 1987 and was most recently appointed Assistant Chief of Naval Staff (Aviation & Carrier Strike) and Rear Admiral Fleet Air Arm in February 2019.