A Midshipman’s Guide to Sea Power

by MIDN Xavier Hayward

Key takeaways

• Sea Power is the relationship between economics, the state and military capabilities.

• Australia is critically reliant on seaborne trade and the navy has a crucial role in maintaining Sea Power.

• The strategic environment requires a knowledge of theory as a professional member of the RAN.

Why do I need to know Sea Power? 

Sea Power is not an arcane and esoteric theory, relevant only to captains and admirals. It is the conceptual basis of which Australia’s trade, maritime industry, economic prosperity and military depend. Corbett argues the importance of understanding theory stating:

During war close range accidental factors will force themselves into undue prominence and tend to obscure the true horizon. Such error can scarcely ever be eliminated, but by theoretical study, we can reduce it, nor by any other means can we hope to approach the clearness of vision with which posterity will read our mistakes. Theory is, in fact, a question of education and deliberation and not of execution at all.^[1] 

The changing strategic environment that we find ourselves in requires more than technically proficient sailors and officers; it also requires professionally curious individuals. This is for not only the captain, or a midshipman hiding from the navigator but for the whole of the ships company and by extension any member of the profession of arms in the Royal Australian Navy. In a US naval institute article, LT Misso reflects on the need for further educational development stating, “We develop surface warfare officers who can stand on their feet for hours on the bridge, but cannot fathom how the position of their ship in the ocean impacts the global economy.”^[2] As a member of the RAN, you must have a stake in your own service, to be both learned and technically competent as a steward of our profession.

What is Sea Power?

Sea Power is much more than sleek, grey, messengers of death adorned with numbers on their bows. Sea Power is not only concerned with militaries, their navies and the effects they can produce. It is an integrated national endeavour, the sum of military and non-military capabilities led by the government of the day. At its core, it is a complex relationship between economics and the military that is responsible for the security and prosperity of the nation. 

The economic facet of sea power is the nation’s capability to operate and sustain trade and a profitable maritime industry. This includes but is not limited to fishing fleets, maritime trade and shipping, the harvesting of natural resources, conducting maritime research, using sea lines of communication (SLOCs), boosting tourism, recreation and transport and investing in shipbuilding and repair facilities. 

The military component of Sea Power is multifaceted. It is concerned with the defence and preservation of the nation’s maritime industry through an integrated multi-domain approach to secure or deny control of the sea. To have sea power, a nation’s maritime force must retain the capability to operate freely in the maritime domain or, instead deny an adversary’s access and ability to operate in such domain through the threat or actual use of force. There are three definitions, all of which are related, that aid in understanding the military aspect of Sea Power: sea control, sea denial and command of the sea. 

Sea control exists when a country has the freedom of action to use an area of sea for its own purposes for a sustained period, and if necessary, deny its use to an adversary. Sea control applies to the adjacent domains of the airspace above, the water mass and seabed below as well as the electromagnetic spectrum.^[3]

Sea denial can be as simple as preventing an adversary from securing sea control. Examples of sea denial include the operation of exclusion zones, the maintenance of a blockade or a campaign against an adversary’s trade and logistics distribution networks.^[4] 

Command of the sea is a debated term that has undergone multiple revisions since it was first used by Alfred Thayer Mahan and Sir Julian Corbett. Mahan describes command of the sea as “the possession of that overbearing power on the sea which drives the enemy’s flag from it or allows it to appear only as a fugitive.”^[5] Corbett defines command of the sea as “establishing ourselves in such a position that we can control the maritime communications of all parties concerned.”^[6] There are different degrees of success when one commands the sea ranging from disputed, local and general command. “Local command tends to be temporary, and general command is more likely to be permanent.”^[7] Both Mahan and Corbett realised that absolute command of the sea is an impossibility and that even general command is not a condition of absolute security, but instead a situation in which “opponents could still act, but only at great risk.”^[8] Command of the sea is the strength of a force in a specific area. Modern weapon systems have forced its evolution towards relative dominance and influence projected by a navy in a limited temporal or geographic space.

The origins of Sea Power 

There are two foundational figures in the intellectual history of Sea Power, Alfred Thayer Mahan and Sir Julian Corbett.

Alfred Thayer Mahan (1840 to 1914) 

Mahan was an American naval officer who served during the Civil War, later becoming a naval strategy theorist. He describes the sea as “the great highway of the globe” occupied by maritime technicians, anglers, shipwrights and dockyard employees, all workers “following the sea”.^[9] Mahan understands trade routes as well-trodden paths, now understood to us as SLOCs. He argued that states exploit the sea to produce wealth that funds a strong fighting navy to protect the nation’s trade and deny an adversary’s ability to compromise it, thus creating a cycle of wealth generation and naval protection. Tactically, Mahan was an advocate of large, decisive naval battles occurring in decisive points along SLOCs. This ensured control of industry and trade, and reflects an early understanding of the relationship between economics and the military summating to Sea Power. 

Sir Julian Corbett (1854 to 1922)

Corbett, a British lawyer by training is the second foundational figure to develop sea power theory. Corbett argued the purpose of naval warfare is to “directly or indirectly either secure command of the sea or prevent the enemy from securing it.”^[10] Acquiring command of the sea served to “exert direct military pressure upon the national life of the enemy ashore … and prevent his exerting direct military pressure upon ourselves”.^[11] Corbett understands the navy in a wartime scenario as the governing authority, preventing the passage of merchant shipping and trade via the sea, thus controlling communications, trade and naval movements ensuring Sea Power. This process places SLOC as a primary target of naval warfare, submitting merchant shipping to be as sound a target as a warship, thus waging economic warfare. Although never directly mentioned this theory relates closely to sea denial as seen in history with the Blockade of Germany in the First World War and Germany’s U-Boat campaigns against merchant shipping in the Second World War.

The Impact of Mahan and Corbett

Despite being over one hundred years old, the framework provided by Mahan and Corbett to understand the relationship between economics and warfare retains its utility as the world becomes increasingly interconnected through globalisation. Although technology has changed warfare, the maritime domain in which it will be fought has not. SLOCs and merchant shipping have grown in importance and at the same time have become a potential target for conflict. Mahan and Corbett’s theory of warfare may be realised for a new generation of naval war fighters, in a battle for control and command of the sea.

Why do we have a navy?

The question ‘why we do we have a navy?’ can be answered by simply acknowledging Australia’s geography and the strategic circumstances it faces. Australia is a maritime nation, over 99% of Australian trade travels by sea, undersea cables carry 99% of global internet traffic and there are at times only 27 days of petrol and jet fuel reserves.^[12] Australia’s way of life and economic prosperity are inextricably linked to its ability to exercise Sea Power. This is reflected in doctrine stating Australia must “use the sea when and how we require to, and deter or deny an adversary from acting in such a way that prevents this.”^[13] The 2024 National Defence Strategy recognises that “Australia’s future depends in large part upon protecting our economic connection to the world” and that the lengthy time window prior to conflict has closed.^[14] However, this realisation of Australia’s predicament is not new. Captain Creswell in his report to Parliament reflected upon the innate threat associated with Australia’s reliance on maritime trade in 1902, “The spectacle of some 5,000,000 Australians, with an Army splendidly equipped, unable to prevent the burning of a cargo of wool in sight of Sydney Heads, is only the ordinary consequence of a policy of naval impotence.”^[15] The Navy is the government’s insurance policy; it is the military force that operates in multiple domains to ensure Australian Sea Power is upheld in peace and war.

Notes