Polar Bears are a special unit in Stronghold Legends, and only available to players who are currently playing as the Ice faction.
They are recuited from The Ice Tower, costing 100 gold and 20 honour. You can find out ways to generate Honour in the game here.
Polar Bears are very powerful units on the battlefield, especially in groups, and can quickly annihilate most units without taking a lot of damage.
The main downside is that the cost of recruiting them in gold can be substantial if you intend on recruiting more than one, which is generally how they work best.
Polar Bears can overpower enemy units and are very well defended against ranged attacks by Archers. They are however very slow moving units, and can take a while to get to where you send them.
This is particularly problematic as it allows for Archers and other more agile units to lure them into a trap, fire at them and then run around until the Polar Bears have exhausted all of their health.
They also have no way of defending themselves against aerial bombardment as well, so if you send them on a long journey such as to recapture an estate, it's very important to note that firstly, by sending them on this journey the cirumstances of the estate (such as who owns it and how many troops are stationed there) may have changed significantly once they actually arrive, but secondly, it's important to know that they can be worn down by aerial attack on the way to their destination with no way of defending themselves.
Once they have reached their destination however, they should be able to dispatch of any enemy units pretty quickly. They can also destroy buildings as well, so if you send them to attack an enemy castle, they can easily be used as harrassment units to destroy buildings and then retreating back to the safety of your main army before they start taking any real damage.
Another extremely useful ability of Polar Bears is that they can actually attack castle walls, gatehouses and towers themselves - they do not need siege equipment. This means that they can tear down castle defences of the enemy and create breaches of varying sizes for your troops to rush through, depending on how many Polar Bears you are using.
It goes without saying that if you are playing against a player using Polar Bears, you should place an Engineer's Guild in your castle to try and automatically repair any damage caused by them to your walls before it gets worse. Note however that Polar Bears cannot scale walls or towers, or reach the Lord on the top of an enemy Keep.
They cannot move from ground level throughout the entire game, so while they can destroy an entire castle and all buildings and units at ground level on the map, they cannot win you the game on their own unless an enemy Lord wanders down from the Keep to ground level, in which case he can be attacked.
Any enemy defenders which were stationed on the castle wall will fall down to ground level unless they move before the wall is destroyed. Once this happens, the Polar Bears will also be able to attack those defenders as well. Polar Bears are very well armoured, so if you intend to do any damage to them using ranged units, you must use Crossbowmen- Archers are simply not powerful enough.
Crossbowmen will still take time to do a lot of damage, but they will eventually break through, purely because of the slow movement speed of the Polar Bear. They will also struggle severely in single combat with the more powerful units such as Knights and Frost Giants. Fire can also have a lasting detrimental effect on them due to their slow movement speed, as can freezing because it makes them even more vulnerable to enemy ranged and melee units.
Tip: Polar Bears are well armoured and excellent units for defending key areas on your map. Their attacking and defensive abilities means that they are unlikely to die from sudden enemy attacks on estates, although you must keep an eye on their health and plan ahead in advance when using them to defend such locations.
This is purely because of the extremely slow movement speed of Polar Bears and therefore the time taken for any new reinforcements to arrive. Polar Bears are great units for attacking enemy walls, and if you use a strong enough group you can destroy an entire enemy castle in a matter of seconds. This makes them invaluable and of considerable reliance when playing as the Ice faction.