Warfare, like most things in Oceana, is subject to the constraints of technology and the existence of magic. The level of technology and the existence of magic plays a major role in determining tactics, strategy and of course available weapons. This entry is based upon the current technology level and politcal setup on Oceana.
Oceana exhibits an odd mixture of weapons from various Earth eras. The most common weapons are swords, pikes, bows and cross-bows and similar pre-gunpowder weapons. The weapons listing is typical midieval fantasy Europe. The major limitations on weapons technology is the lack of iron on Oceana and the presence of magic.
Gun-powder weapons exist, but are rare outside of certain areas. Even where guns can be found, they are in short supply due to cost of the gun and the cost of bullets and gunpowder. Matchlocks make up 90% of the guns. Flintlocks are coming in and about 10% of weaons have been converted or remade. There are an extremely small number of other types. Many islands have outlawed gunpowder weapons except for military or police. Ships that carry guns have to bond them. The expense and unreliabiltiy of guns also keeps them out of the hands of most civilians even in areas where guns are made. In areas with few guns, getting ahold of gunpowder just adds to the difficulty.
Cannons also exist, but are even rarer than guns. Cannons are of the muzzle loading type black powder type, mostly in the 4 and 8 pounder size. An issue with respect to cannons was the lack of metals, both bronze and iron. The amount of iron in a single cannon could provide a lot of men with swords, shields and basic armor. It was more important to have the larger numbers of men for defense at many points rather than a single cannon used for sieges. Even multiple cannons would be a problem in a battle. Movement by water of cannons and horses was, and remains, very hard. Cannons were also vulnerable to being lost. They could be lost if the ship they were on was sunk at sea or in the enemy harbor, or if the battle went poorly they would have to be abandoned. Rifles and muskets faired better in this respect. Each soldier could carry their own weapon, both while traveling to the attack, and if need be while retreating.
In this world of water and islands with no really large landmasses, ships can appear on the horizon and attack any island with little or no warning. Only in areas controlled by by the large major powers, with just their core areas covered are there zones fairly safe from piracy and raiding. Maintaining such zones requires a great deal of naval and aerial patrols. Large amounts of money, materials and manpower are used to protect what each power has from raiders, and to a lesser extent, the other powers. Therefore there are very few numbers of troops that can be spared for offensive operations and re-taking of islands. Freeing up troops can be done, and has to be done, to put down pirates and occasionaly raid other powers. Troops can also be hired for operations. This is especially common among the more independent city-states in the borderlands area. Border security is fairly high to prevent raiders. As such smugglers have a hard time unless moving very small items such as by air. In a historical context this is similar to the ancient Greek Delian League and England's Royal Navy in the 1700s thru the early 20th century.
Major warfare is relatively rare. There are no countries that can field a major expeditionary army without leaving multiple rear area islands poorly defended, or undefended. Most places also have an armed citizenry as a home guard. Besides having to field an expeditionary army, the conquering nation would have to tie down a good portion of their troops subjugating the occupied land. This would tie down the strategic reserves. Instead, islands will be picked up that are either uninhabited, or that are in need of stabilization. The limitation on troops is a matter of money to pay the troops, and total population. The current demographics do not provide a lot of military manpower. Nor is there currently a desire to maintain a large army. The eastern island nations such as Athenian Confederation and Egypt do not have the civilian support for a large military. This is similar to the United States and western Europe at the end of the 20th century on Earth.
On a historical time period, Egypt and the Selemos Confederation were able to mount major military operations prior to the Monsters Plague. It was at that point that monsters were pushed to the west and many islands were settled. Even then manpower was an issue, just not as much of an issue as it is now. All the major powers found it to be in their long term interests to permit the minor military powers, such as Elves, Dwarves, Nekojin and Anglo-Saxons to found settlements on islands the major powers had cleared, or on nearby islands. The presence of nominilally friendly forces against the monsters was more important than keeping areas exclusivly theirs. The major powers also had the chance or choice of bring such minor settlements into their sphere of influence anyway.
Most nations decided on larger settlements which are tougher to raid since there would sufficient manpower to put up a good fight. Small, scattered, weak settlements would be prone to raiding. One of the basic strategic decision to be made by each power is how to hold and protect their settlements, towns and cities. The general concensus was that having powerful nobles or towns in scattered parts of the civilized world was better than expanding only upon the direct edges of settled islands. Such areas will have a powerful noble or a wealthy company backing the settlement. This models the early colonial period in North America, circa 1600 to mid 1700s. It is this pattern of settlement that set up the boundries for future fiefs, independent counties, city-states and baronies.
Kings or goverments grants a powerful noble or a company not just a single island, but a group of islands. The leaders are granted full rights to all the islands, subject to the arrangement with the granting authority. They will choose the most appropiate island for their initial settlement. What makes a site good for a new town generally is a combination of a good harbor, good farm land, easially defended and natural resources such as ore. Such scattered powerful sites would be able to defend themselves from barbarian raiders better than lots of smaller, less powerful sites that were closer together and closer to the edge of the civilized islands. Governments would rather have islands that can easily defend themselves instead of having the costs of provide military help to numerous smaller places. This results in many islands being by-passed in resettlement. The island have been lightly explored, and even previously settled, but are not important enough, economically or militarily to settle immediately. Also, such scattered powerful islands could even intercept raiders trying to get deeper into the core islands.
Unlike the originial Roman Empire, expanding borders on Oceana just increases expenses. On Earth, expanding borders provided strategic depth and provided a very peaceful rear area for development. On Oceana there is the need to guard against raiders who are relatively low tech, similar to Earth Vikings. In an island enviroment this means fortifying and keeping fortified islands, including ones that are far from the frontier. Raiders can hit anywhere at any time. The army can only hold islands they are actually on. This has lead to islands being largely settled and developed before another island is colonized. The ocean enviroment also means naval patrols that are expensive. This in turn lead to a form of feudalism once the concept was introduced by the Anglo-Saxons and Norwegian vikings.
Unlike the creation of the British Empire in the 1800s, there are few societies with lower technology levels waiting to be subjugated. The British were able to create their Empire by grabbing ports in far parts of the world from England. The areas they established as colonies were already settled, and were able to produce and sell raw materials and agricultural products that England wanted in exchange for English manufactured goods. The colonies were created when the locals threatened British mercantile interests, at which point the military stepped in. On Oceana, most of the monster tribes are not settled enough to be conquered. The monster tribes can normally only be killed or enslaved. The humans and allies can not conquer the tribes and rule through indigeonous leaders.
There are few, if any countries that can afford to station a garrison, or re-settle every abandoned island they find. The technology does not exist to cheaply bring food and other support to sufficient sized garrisons to protect each and every site. Food ship's still travel by sail. While moving food by sea is common, imports of food do not provide the major food source for all but a few islands. Garrisons will be found on selected islands along with colonists who grow food and such for themselves and the garrison. Abandoned islands are only resettled when there is sufficient number of colonists and sponsors available. Many islands are by-passed in favor of ones that are more recently abandoned or known to be cleared of monsters. Adventurers and other groups can easily get permission, and a grant of nobility (if appropriate) to settle an area. Almost always, the king will grant not just one island, but a cluster of islands. Protecting it's own borders by clearing the nearby islands of monsters and other threats is up to the new noble or colonizing company.
Land warfare in Oceana is a relative set state of affairs. Moving men and equipment is a slow process, both via ship and on land. Troops move overland no faster than pre-railroad speeds, in other words they either walk or ride horses. Ten or so miles a day for an army of any size is a good speed for most armies in Oceana. This is due to lack of roads, training, rough terrain and lack of supplies. Although there are a very small number of railroads in certain areas, they are small, lightweight, usually wooden tracks, slow and costly. They only cover a small area of the most developed areas. The fastest normal method of travel is by foot, wagon or horse. A small number of flying brooms and carpets and similar magical items are around, however, since they are very costly to make, rare and mostly owned by wizards, they are of no real use in moving significant numbers of troops. Horses are also costly in most areas, hard to travel with between islands and therefore mostly not used in actual warfare.
Land battles are primarily between small armies and take place outside of cities. Armies are armed with the areas main weapons and armor. This is usually a mixture of pikes, sword & shield, and archers. There are very small contingents of magical troops and small number of musketeers/riflemen. Troop types go the range from (poor) serfs with clubs, spears and whatever is at hand, to (elites) Roman Legionaries style units. Since horses are very expensive to maintain on the islands of Oceana, the amount of cavalry is quite small for most areas. Cavalry units tend to be formed from nobles who provide their own horse and gear, or are supported by nobles. The main area for cavalry units is Egypt. The use of horses is unusual for invasion groups. Horses do not travel well on the ships of Oceana, nor are they easy to unload fast enough for an invasion. Cavalry units are thus primarily home guard defense units. Oceana has the stirrup so actual mounted combat exists, normally light lancers instead of heavy knights. Cavalry are used more as scouts than for actual combat.
Battles tend to be decisive in most cases. The primary reason is to capture the island that is invaded. Mostly the campaign is over the large city or town on the island. The entire island tends to capitulate once the major city on it capitulates. The citizens and soldiers will often be sold into slavery, sometimes to off island bidders or just to the new landowners who conquered them. Seiges are rare and difficult to impose except by a major power. A seige requires control of the surrounding country side, the waters near the city and the air space above the city. Seiges are aimed at taking the city by one means or another. This could include starvation, breaching the walls or even creating enough economic pain that the city will give up. Actual submission by running the city out of food is tough due to magical re-supply and water purification though. Magic in Oceana can not create food or water out of nothing, but it can transmute organic matter into food, and purify water based liquids into drinkable water. Since most cities have a limited amount of magic users and magic components, it can be done.
Fortifications range from the simple to the far more complex. They range from simple wooden walls to large stone walled cities. Most reflect the existance of magical aerial units which have existed in small numbers for many generations. Most cities cities have at least a wall with gatehouses. Most of these are of stone, but due to where they are located and the age of the city, and the threat level and the cost, they might be of wood. Medieval European style castles do exist, however they are mostly only built anywhere other than the borderlands or frontier areas. The mid-1700's style fort from Earth that is more likely to resist magic are much more common over the past 1,000 years. A side benifit of this is the concurrent ability to resist the new gunpowder weapons such as cannons. European castles are designed to protect against land based troops only. Oceana fortifications tend to be flatter and have bunkers and limited anti-air protection. The flatter structures permit moving troops to intercept glider or broomstick or magic carpet landings. There are still stone walls such as American coastal forts to protect against conventional troop attacks. Siege engines such as trechbucket and catapult are well known. The ancients had them, and the art has never been lost. Most harbor cities have them to defend against ships. Raiders do not have the time to construct such engines, nor to carry them from island to island. Larger armies can move seige engines, and will use them for major campaigns. Cannons are starting to be used, and magic has been used both defensively and offensively for centuries.
It is very hard to take and garrison islands. The limited land fighting between city-states makes large armies uncommon; the smaller lords do not have the resources for extended multi-month battles or occupations. The need ot maintain garrisons even on the home islands limits the troops available for offensive operations. Most islands have a well armed, albiet poorly trained, militia in case of raiders. Also, the existance of magic items can make for very asymetrical warfare. A small party of powerful fighters and mages can wreck havoc on a small garrison, even destroying the garrison. Such small parties though can't hold an area against local opposition, so at best they can be a thorn in the side of the holders. Reprisals against the locals by the invaders only work if the invader has the ability to totally repopulate the island, which is usually not the case. Barbarian raiders, while mostly a problem in the outer areas, are only interested in hit and run raids for loot and slaves.
Magic based units also exist. Weapons are usually enhanced swords or magical wands. Mages will have access to the usual spells such as sleep, fireball, lightning bolt and telekinetic attacks.
Naval movements are limited to the speed of sailing ships. The average speed is around 5 knots, although some specialized ships can make 10 knots and the rare courier boats (trimarans) can make up to 20 knots in the correct sea conditions. The sail plans of many of the larger city-states are from mid 18th century to mid-19th century. Oar powered galleys are common in the Horse latitudes, and variations of the viking long ship are common among the smaller island nations in the northern and southern areas. Almost all ships are made of wood. Some companies are experimenting with iron frames and wooden hulls. There are rumors that dwarves are building iron hulled ship's that are propelled by steam.
Piracy is an on going problem for Oceana. There are so many small city-states, many of whom have little to no ability or, sometimes reason to keep pirates at bay. There are even out and out pirate havens, where it is very easy to obtain a letter of marque. Naval piracy exists in conjunction with slavery. This is a pre-industrial world, so slavery is very common. This is especially true in a couple of areas. Think of the Silesian Confederacy from the Honor Harrington universe.
The lack of metals prevents the common deployment of ships that employ cannons. Conventional weapons on most ships (large and small) will be ballista, catapults, bows, and similar equipment. Boarding parties are still the mainstay of naval and piracy action. These consist of both conventionally and magically armed troops. Cannons are very rare, and only seen on warships of major powers or ones owned by very rich merchant houses. Most often such vessels will be Q ships where the cannon is hidden until the last minute. Cannons are similar in design to mid-1800's on Earth. In the past few years that has changed in Salycis. Salycis has started to deploy a new form of cannon. Instead of a cast iron barrel, it is a high grade of steel. It is also breach loading using shells.
Aerial units add literally another dimension to combat. There are no true paratroopers, but the ability to land even small numbers of men and material behind normal lines add complications to both strategic and tactical issues. Any city-state or landmass is open to aerial raiding from neighbors' nations or even from pirates. All aerial units are either magical item based or fantasy creature based. Such units are rare and expensive, but very important at times. Units are very small, almost never over the equivilent of a squad in size. They are the most costly units in Oceana, and as such generally only major powers will have them. The occasional independent island lord may have one or two magical item based units, but almost never have fantasy creature based units. Aerial units can be hired, and often are. Some units are totally free-lancers and some are units from national armies that are trying to support such units.
Units range from flying broom mounted troops to dragon mounted troops. Creature based units have a very high maintainence cost and therefore are few and far between (think how much food a dragon can eat each day).Regardless of how much such units cost, they can be very important at times. Since such units can move at speeds up to 100 miles per hour, just the fact that the unit exists can cost the opposing force a huge amount of money, troops and supplies to counter them. The major powers and large merchant houses keep their aerial units active by using them for recon, messages and important mail carriers. Of course it costs to use these units, but since it's the fastest way of getting information from one island to another, and the quickest way to find out what is happening around where you live, it's worth it.
Flying units equipped flying carpets and broomsticks can be of great use. Such aerial units can act like modern day fighters and to a lesser extent bombers. This gives a whole new meaning to the term carpet bombing. Magical item based flying units can use bows, cross bows, wands and cast spells in both an offensive and defensive role.
The closest thing to Special Forces troops are adventuers and raiding parties. Both are fairly common outside of the core islands. Some major powers are starting to train and use their elite units as special operations troops. However, since such troops have a large variety of other uses and very little in the way of commando uses, special operations units are even rarer than flying units. The major limitation on special ops units is cultural. There is no real percieved need for such a military unit, and the type of warfare on Oceana doesn't fit very well.