The Rangers of Ithilien or Rangers of the South, much like their distant cousins the Rangers of the North, were a military group whose purpose was to defend Ithilien, the gate to Minas Tirith, and to prevent Haradrim and Orcs from entering Gondor.
They were selected from the descendants of the people who had dwelt in Ithilien before it fell from Gondor's control in TA 2901. They were camouflaged in green and brown cloaks, and fought in a style resembling modern Guerilla Warfare: that is, stealth, sneak attacks, etc. They often crossed the Anduin in secret to harass the forces of the Enemy in Gondor's old domain.
The Rangers often conducted ambushes against the Haradrim (digging traps for their Mumakil), attacked Orc scouts, and protected the old road from Minas Morgul to Osgiliath. Ranger attacks were feared and dreaded by all of the enemies of Gondor, being able to slaughter entire battalions at unawares. Just a hundred to a few hundred of these trained archers can take out companies multiple times their size. In the Two Towers book, a company of Faramir's rangers waylay a battalion of Haradrim, killing even their mumakil. They were very deadly with a bow (which was their primary weapon) and they were nearly as skillful at stealth as the elves, even if they had only heard of them in stories at the fireside. Their chief at the time of the War of the Ring was Faramir, Captain of Gondor, and future Steward of Osgiliath and Prince of Ithilien.
From Peter Jackson's MovieEdit
This specialisation and forte for covert tactics, which naturally befitted the camouflaged Rangers, was illogically forgotten by the ever more twisted Denethor II, Steward of Gondor. At his bidding his sole surviving son and heir, the venerable Captain Faramir, was ordered to take 500 or so Ithilien Rangers into the ruined city of Osgiliath. Faramir himself disagreed with this decision strongly, knowing - as arguably the finest ranger alive in Gondor - that his men were ill suited for fighting alongside the metal clad regular infantry in the gaunt ruins of an urban battlefield. Though the Ithilien Rangers could and did ambush Orcs from the confusing labyrinth of (for the Orcs at least) barely identifiable or distinguishable buildings, overall, the armies of Mordor held a significant advantage in times of full assault. The Ithilien Rangers were best used in mobile ambush, using their excellent camouflage to blend into the forest. Though individually skilled as archers and swordsmen, they still needed to fight in decent numbers to survive let alone defeat the by far more numerous Mordorian forces. Spread very thinly over several miles of the West Bank of Osgiliath, the Rangers had been deprived of much of their impact as an otherwise dangerous unit. This was dramatically proven during the last Battle of Osgiliath. As thousands of Orcs poured as a flood from the Anduin itself into the West Bank, the Rangers were simply overwhelmed, along with the Gondorian Soldiery. Arguably no matter how bravely the Ithilien Rangers fought, against a vanguard of over 10,000 Orcs alone followed by another 65,000 in the main first wave, there could be no victory for the comparatively tiny Gondorian garrison. Amongst the smouldering ruins of Osgiliath, over 300 Ithilien Rangers perished, around the same number of casualties the Gondorian Soldiers had suffered. Small groups were cut off in the battle and slaughtered man by man. In some cases, lone Rangers could be trapped on the rooftops and upper levels of buildings and killed with ease (one Orc in Peter Jackson's film takes particular pleasure in killing one such isolated Ranger) As a result of the fractal nature of the Ithilien Ranger formation during the last Battle for Osgiliath, Orcs could swarm around them, driving deep behind the defence lines and surrounding the men defending them. Also, at night, these Orcs had another advantage, as Orcs thrive in the darkness which is their comfort zone. By the morning hours, the battle was turning into a massacre, and now the Ringwraiths upon their Fellbeasts had arrived to terrorise the Men of Gondor. Faramir saw the bloody writing on the wall and reluctantly issued the order to retreat, though he did so enthusiastically to ensure as many survivors as possible. Madril, Faramir's second in command and fellow Captain, was cut down by an Orc as he was distracted by a swooping Nazgul. Gothmog would personally skewer him with a spear after the Gondorians had retreated. In the desperate and rather chaotic retreat back to the safety of Minas Tirith, dozens more would be killed by the Nazgul upon their Fellbeasts. Only with the intervention of Gandalf the White upon Shadowfax, were the Nagzul prevented from killing even more of the crestfallen Gondorians.
After this terrible battle, Faramir and his few surviving Rangers recovered behind the walls of Minas Tirith. Even so, Denethor II had reached new levels of madness and decreed that Faramir and his men should attempt to recapture Osgiliath - which was by now occupied by over 200,000 Orcs, Easterlings, Haradrim and worse. Leading 200 mounted Rangers, an armour plated Faramir heroically obeyed his miserable orders. Gandalf the White had pleaded with Faramir not to go ahead with the suicidal attack, which was indeed doomed to failure in any case. However, Faramir was deeply depressed over his own father's hatred of him, and so decided death in battle was a more noble end. His loyal men would follow him to whatever end. None survived, save for Faramir. In the film, Gothmog himself gives over 5,000 Orc Archers the order to unleash a catastrophic hail of arrows into the Gondorian force. Presumably this is what wiped them out. During the subsequent Siege of Minas Tirith, perhaps only a handful of Rangers were left over to help defend the city, and of these probably none survived as the city was breached. Truly, the Ithilien Rangers were badly misused during the latter days of the War of the Ring, which basically led to their virtual annihilation - a grim testament to the madness of the then Steward of Gondor.