Naval Warfare: A Journey from Ancient Galleys to Autonomous Weapons and the Role of International Law


“Naval warfare” is a term used to denote “the tactics of military operations conducted on, under, or over the sea.”1Wayne P. Hughes, ‘Naval Warfare’ (Britannica, 22 August 2022) <> From using ships as vehicles for transporting troops and arsenal to introducing autonomous weapons, naval warfare has advanced significantly. In A strategic planning and a tactical execution at sea can help securing a victory at naval warfare. This necessity makes it essential for military forces across the globe to explore and invent advanced weaponry that can neutralize the threat with a single hit. This article aims to explore the evolution of naval warfare and how it has influenced the international law governing the maritime domain. Subsequently, it will examine the recent technological advancements that are changing the nature and scope of war beyond the current scenario.

The Evolution of Naval Warfare

Human interaction with the sea dates back as far as 480 BC, when the first naval battle was fought in the narrow straits of Salamis, where the Greek naval forces defeated the Persian fleet.2The Editors of Encyclopedia Britannica, ‘Naval Warfare’ (Britannica, 9 June 2023) <>

In ancient times, galleys were used for war at sea, with rams as the primary weapons. For instance, in the Battle of Salamis, a warship was about 75 feet long and 15 feet wide, with about 90 oars arranged in three banks on each side, one rower to an oar.3The Evolution of Naval Warfare (Naval History and Heritage Command, 1949) <> After the time of Alexander the Great, ships reached a length of 200 feet and a weight of several hundred tons, and some mounted catapults.4Ibid

The introduction of guns caused a significant change in the design of warships. This was because galleys were highly susceptible to gunfire, and incorporating both guns and rowers into the design proved challenging. Initially, the Venetians attempted to mount a small number of fixed cannons in a forward deckhouse.5Ibid The effectiveness of these guns against enemy rowers led admirals to demand an increase in their number.6Ibid

Naval steamships were introduced In the mid-19th century in the form of  ancillary crafts, such as gunboats and dispatch vessels.7Ibid Subsequently, the integration of shipboard devices led to the development of the dreadnought battleship, which carried calibrated guns with twice the effective range of pre-dreadnoughts.8Karl Lautenschläger, ‘Technology and the Evolution of Naval Warfare’ (1983) 8(2) MIT <> accessed 15 June 2023.

The submarine entered the scene as the next of the novel weapons during WWI. When used against warships, the submarine was, like the surface torpedo boat, a defensive weapon or a means of harassment. As a commerce raider, however, the submarine opened a new dimension in naval warfare.9Ibid During World War II, two types of guided ordnance were introduced to naval combat: the homing torpedo and the anti-ship missile, which were radio-controlled missiles or glide bombs, and all were launched from land-based aircraft.10Ibid

As we enter the modern era and the advent of Artificial Intelligence (AI), there is a shift toward the use of AI-controlled and autonomous weapons. This topic will be further explored in the upcoming section titled ‘How the future looks like?’

The Evolution of International Law on Naval Warfare

From Paris Declaration (1856) to the Adoption of the Oxford Manual (1913)

The origins of naval warfare legislation can be traced back to 1856. States would issue official licenses to private individuals to attack enemy ships in armed conflict, but the Paris Declaration (1856) banned this practice, leaving the fighting to State warships alone.11ICRC, ‘Paris Declaration, 1856’<> Succinctly, marine operations were thus limited to state actors.

Subsequently,  an effort was made to extend the principles of the first Geneva Convention for the amelioration of the wounded in the armies (1864) by convening the second diplomatic conference in 1868,12ICRC, ‘Geneva Convention, 1864’ <> which confined itself to the ground forces to sea warfare by adopting the Additional Articles.13ICRC, ‘Additional Articles to the 1864 Geneva Convention, 1868’ <> Despite their efforts, the Swiss Federal Council in Geneva could not get any ratifications for the Additional Articles, rendering them unenforceable.14Ibid The Franco-German War of 1870-71 and the Spanish -American War of 1898 emphasized the importance of adaptation of maritime warfare laws, and it was not long before the Council requested the International Committee of the Red Cross (ICRC) to prepare a draft and convene a conference with regards to this subject.15ICRC, ‘Hague Convention (III) on Maritime Warfare, 1899’ <> However, the Czar of Russia took the initiative and successfully convened the conference at the Hague in 1899.

One of the most vital outcomes was adapting the rules laid down in the first Geneva Convention to the naval war.16Ibid This Convention was revised and replaced in 1907 by the Hague Conventions. Among the seven treaties related to the naval operations that were adopted in the 1907 Hague Peace Conference, the following six conventions continue to be in force:

  • Convention (VI) relating to the Status of Enemy Merchant Ships at the Outbreak of Hostilities;
  • Convention (VII) relating to the Conversion of Merchant Ships into War-Ships;
  • Convention (VIII) relative to the Laying of Automatic Submarine Contact Mines;
  • Convention (IX) concerning Bombardment by Naval Forces in Time of War;
  • Convention (XI) relative to Certain Restrictions with regard to the Exercise of the Right of Capture in Naval War;
  • Convention (XIII) concerning the Rights and Duties of Neutral Powers in Naval War.

In Convention IX, the first article confirms the principle that “bombardment by naval forces of undefended ports, towns, villages, dwellings, or buildings is forbidden,” whereas, Article 2 of the same Convention established the use of bombardment by the naval forces of military objectives in undefended towns as legal.17ICRC, ‘Hague Convention (IX) on Bombardment by Naval Forces, 1907’ <> It is also notable that Convention No. VIII and portions of Nos. XI, and XII, respectively, have continuing significance, i.e., these conventions are observed internationally as customary international law even for the states that have not ratified these Conventions.18J. Ashley Roach, ‘The Law of Naval Warfare at the Turn of Two Centuries’ (2000) 94 Am J Int’l L 64

In accordance with Article 7 of Convention (XII) of 1907, customary rules of prize law were set out in the 1909 London Declaration concerning the Laws of Naval War. Per Article 46 of the 1909 Declaration of London, neutral merchant vessels taking “a direct part in hostilities” could be attacked without warning.19ICRC, ‘London Declaration on the Laws of Naval War, 1909’ <> Although the Declaration officially never came into force as the British House of Lords rejected it, and so it was not ratified by any signatory,20ICRC, ‘London Declaration on the Laws of Naval War, 1909’ <> its rules were recognized by several belligerent States during WWI.21ICRC, ‘Final Protocol to the Naval Conference of London, 1909’ <>

Summarizing the Laws Before the World War I

The pre-1914 law governing naval warfare can be summarized as follows:22This summary is based on a similar summary in L. Doswald-Beck, “The International Law of Naval Armed Conflicts The Need for Reform,” which, in turn is derived from the 1909 London Declaration concerning the Laws of Naval War, and the 1913 Oxford Manual. (a) Enemy warships and naval auxiliaries could be attacked outside neutral territorial seas. (b) Enemy merchant vessels could be captured outside neutral territories and could be attacked if they resisted visits, search, or capture. Captured enemy merchant vessels could be destroyed for military necessity. (c) Neutral merchant vessels could be stopped and searched outside neutral territorial seas and could be captured if they breached a validly declared blockade or carried contraband. (d) Neutral merchant vessels performing un-neutral service were treated as enemy merchant vessels and can be attacked. (e) Certain vessels were exempt from attack or capture as long as they did not participate in hostilities. (f) Shipwrecked persons were not legitimate targets. (g) It was permissible for enemy merchant vessels to fly false colours and disguise themselves unless they did not directly participate in the hostilities. This use of false flags was inconsistent with the practice in land warfare. 

World War I

Given the role of naval arms in WWI, primarily the first use of submarines as part of naval fleets, the Institute of International Law adopted a more comprehensive compilation of the law of naval warfare entitled The Law of Naval War Governing the Relations between Belligerents, also referred to as the Oxford Manual of Naval War. The Manual contained 116 Articles, with one additional Article. The Manual forbade the use of torpedoes “which do not become harmless when they have missed their mark” and automatic contact mines in the open sea, whether “anchored or unanchored.” Furthermore, on the issue of bombardment of undefended ports, the Manual adopted the same rules as laid down by its predecessor in Convention (IX) of 1907.

Post World War I up to World War II

The advent of submarines in World War I (WWI) made it almost impossible to effectively abide by the rules and regulations laid down in the previous treaties and conventions. Submarines would attack enemy merchant ships without warning and without identifying and placing civilians boarding in a safe space prior to the destruction of the ship.23David T. Lee, ‘The Principle of Proportionality in Maritime Armed Conflict: A Comparative Analysis of the Law of Naval Warfare and Modern International Humanitarian Law’ (2021) The pre-war presumption of innocent, unarmed civilian-manned merchant ships proved largely false, as civilians were found on armed ships that were considered military objectives and classified as naval auxiliaries.

During the interwar period, a number of attempts were made by Britain to abolish submarines. Notably, in the Washington Conference of 1922, an effort was made to make submarines comply with the ‘universal rules’ requiring them to follow the protocol before seizing or attacking a merchant’s vessel. However, the treaty could not come into force as France failed to ratify the treaty deemed necessary under Article 6 of the same accord.24ICRC, ‘Washington Treaty on Submarines and Noxious Gases, 1922’ <>

Again, in 1930, a set of rules for submarine warfare were developed under Article 22 of the London Naval Treaty, later reaffirmed in a 1936 Procès-Verbal (the London Protocol of 1936). During the Spanish Civil War, the Nyon Agreement attempted to prevent submarine attacks on merchant ships in accordance with the International Treaty for the Limitation and Reduction of Naval Armaments, signed in London in 1930 and Procès-Verbal (1936).25ICRC, ‘Nyon Agreement, 1937’ <>

During World War II, the same violations of international law that occurred in the previous conflict were repeated. Instead of taking enemy merchant ships and their civilian crews to prize courts, belligerents often destroyed them because they were considered to be closely integrated with enemy armed forces. Both the Allies and the Axis powers utilized submarines as strategic weapons in naval warfare.

Contemporary Treaties on Naval Warfare

The two most important documents in contemporary times relating to warfare in the maritime environment are the Second Geneva Convention of 1949 and the San Remo Manual on International Law Applicable to Armed Conflicts at Sea, 1994.

The Second Geneva Convention of 1949 for protecting the wounded, sick, and shipwrecked, as supplemented by a few provisions of the 1977 First Additional Protocol (AP I) to the 1949 Geneva Conventions, constitutes the set of treaty-based rules that govern the conduct of war at sea today. From a targeting perspective, this Convention re-emphasized that hospital ships are exempt from attack or capture (Articles 22, 24, 25 of AP I ), added medical transports (Article 30 of AP I ), medical aircraft (Article 39 of AP I ), and small coastal rescue craft (Article 27 of AP I ) to the exempt category, and provided additional details indicating how exempt vessels are to be marked under Article 43.26W. J. Fenrick, ‘Legal Aspects of Targeting in the Law of Naval Warfare’ (1991)

The most recent and eminent international document articulating the modern law of naval warfare is the San Remo Manual on International Law Applicable to Armed Conflicts at Sea, 1994 ( San Remo Manual), prepared under the auspices of the International Institute of Humanitarian Law.

The San Remo Manual is a codification of customary international law, an integration of existing legal standards for naval conflict with the Geneva Conventions of 1949 and Protocol I of 1977. The Manual is divided into six comprehensive parts: General Provisions, Regions of Operations, Basic Rules and Target Discrimination, Methods and Means of Warfare at Sea, Measures Short of Attack, and Protected Persons, Medical Transports, and Medical Aircraft.27ICRC, ‘San Remo Manual on International Law Applicable to Armed Conflicts at Sea, 1994’ <> accessed 15 June 2023. Notably, the San Remo Manual incorporates the requirement to avoid targeting civilians directly, it includes the principle of distinction, acknowledging the lack of formal treaty provisions but ultimately making a conclusory statement affirming the requirement as “an essential element of that body of law, no matter how inchoate…”28David T. Lee, ‘The Principle of Proportionality in Maritime Armed Conflict: A Comparative Analysis of the Law of Naval Warfare and Modern International Humanitarian Law’ (2021) In addition, it assimilates the principle of proportionality to mandate an assessment of the military advantage gained against the harm inflicted on civilians or other protected persons while completely embracing the definition of military objectives in Article 52(2) of AP I.29Ibid

What Does the Future Look Like?

With technological advancements and Artificial Intelligence taking over the world, it is not a surprise when we see the same in the field of naval warfare. With the advent of autonomous weapons systems (AWS) at sea, predicting the near-apocalyptic future is not wrong. Weapons that today are being remotely controlled might, in the future, be transformed into AWS. Such military advancements have profound implications for warfare’s future and threaten world peace and raise some serious questions on ethical concerns.

An autonomous weapon includes any armament that “selects and applies force to targets without human intervention.”30ICRC, ‘What do we need to know about autonomous weapons’ <> accessed 15 June 2023. The only human involvement required is to activate the weapon, but “they do not know specifically who or what it will strike, nor precisely where and/or when that strike will occur.”31Ibid The autonomous weapons are triggered by sensors and software and would attack anything that the sensors detect as a ‘target profile.’32Ibid This poses an acute threat to the civilian population as the outcome of such is both difficult to predict and control,33ICRC, ‘Autonomous weapons: The ICRC remains confident that states will adopt new rules’<> accessed 15 June 2023. thus opposing Article 36 of AP I,34“In the study, development, acquisition or adoption of a new weapon, means or method of warfare, a High Contracting Party is under an obligation to determine whether its employment would, in some or all circumstances, be prohibited by this Protocol or by any other rule of international law applicable to the High Contracting Party.” the rule of customary International Humanitarian Law (IHL) declaring civilians and persons hors de combat must be treated humanely, and Martens Clause.35“In cases not covered by this Protocol or by other international agreements, civilians and combatants remain under the protection and authority of the principles of international law derived from established custom, from the principles of humanity and from the dictates of public conscience.”

Despite the ICRC calling for a political response to the use of AWS, countries continue to develop these weapons. For example, the United States Navy is transitioning towards a mixed fleet of crewed and autonomous vessels, which are quickly becoming operational systems.36Malcolm Davis, ‘Robots at war: The future for autonomous systems at sea in the Indo-Pacific’ <> accessed 15 June 2023. This indicates a future naval warfare environment where autonomous robotic systems operate alongside traditional warships and submarines. Similarly, the Royal Australian Navy has released its own Remote and Autonomous Systems-Artificial Intelligence (RAS-AI) strategy document, outlining its plan to develop and incorporate such capabilities through 2040.37Ibid India is also pursuing Unmanned Underwater Vehicle (UUV) capabilities for undersea surveillance, while China seeks to develop advanced UUV and Unmanned Surface Vehicle (USV) capabilities, as evidenced by the UUVs displayed at their recent 70th-anniversary military parade.38Ibid

Thus, it is highly probable that in the near future, human soldiers may be replaced by AI-dependent weaponry. However, it is also pertinent to point out the conundrum of what might be a breakthrough for the military could potentially become a liability for humanity.


In conclusion, the evolution of naval warfare has been instrumental in shaping the outcomes of historical conflicts, with naval supremacy often proving decisive. The development of advanced weaponry and technological advancements, including the emergence of autonomous weapons systems, has drastically transformed the nature and scope of naval warfare. However, this development of maritime weapons has not proceeded unregulated by the international community, as IHL has, for centuries, attempted to codify laws regarding naval warfare, aiming to strike a balance between the two underlying principles of military necessity and humanity. As we gaze into the future, it is evident that the integration of Artificial Intelligence and autonomous systems will continue to reshape naval warfare, presenting both opportunities and challenges for global security and peace.


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Ali Abbas Gilani
Ali Abbas Gilani is a B.A. - LL.B. student at Lahore University of Management Sciences (LUMS). He is deeply interested in International Law and Policy, specifically International Humanitarian Law.