It is a scene right out of the old Wild West, rifle-toting soldiers galloping over the rough hills of the frontier in search of "culprits" whohave been raiding isolated farms.

This frontier, however, is the Rhodesia-Mozambique border. The soldiers are members of Greys' Scouts, the Rhodesian Army's Mounted Infantry Unit - one of the few cavalry units still operating and the only one still fighting a war, the Rhodesians like to boast. The "culprits" are black guerrillas waging a rapidly growing war against Rhodesia's white-dominated government.

Thoe horse has become the newest weapon in Rhodesia's four-year-old counter-insurgency campaign, crucial in bush skirmishes for the same reasons the U.S. cavalry played an important role in settling the American West: soldiers on horses are faster than soldiers on foot, horses are able to travel rough terrain and are relatively quiet.

The recent establishment of the mounted unit reveals much about the type of war the Rhodesians are fighting and their problems.

Limited foreign exchange and U.N. economic sanctions have left the troubled southern African country lacking the resources and contracts for the purchase of sophisticated equipment and arms: all military supplies must be bought through a complex underground network.

Tanks, for example, are too expensive and difficult to obtain through the arms black market. Tanks also require gasoline, which is tightly rationed in Rhodesia due to limited supplies. So the Rhodesian Army has been forced to use alternatives, such as horses.

In this war, the alternatives can often be just as effective Guerrilla attacks have so far been limited to the rural areas, the lush mountain terrain in the east, the thick bush in the north and the sub-tropical scrub in the south.

Most attacks are on white farms or isolated African villages. This means a large part of the army's job is patrolling or tracking small guerrilla bans, for which four-legged animals are the most useful means of transport.

Last year, Greys' Scouts played a vital part in a punitive raids across the Mozambique border - when Rhodesian troops destroyed several guerrilla bases and blew up over 50 tons of military supplies - and in defensive operations in all five war zones, according to Capt. Hamish Mann, a 21-year veteran of the British army who arrived in Rhodesia last year to become second-in-command of the mounted troops.

"People think modern warfare requires modern strategy. That's not the case always. Reviving the mounted infantry has given the army a new flexibility," Mann explained.

Sgt. Roy Elderkin, chief instructor of the unit, pointed out its advantages.

"We can move three times as fast as a regular infantryman, covering as much as 50 kilometers (about 31 miles) a day. When tracking terrorists you can pick up spoor two or three hours old and close in on them in an hour."

Horses, the troops say, give the Rhodesians a psychological advantage. The commander of the Greys' scouts, Capt. A. P. Stevens, said that "Africans are traditionally terrified of the animals. You'll find very few Africans in this part of the world who have ever made use of horses."

Only one-third of the cavalry unit is black, compared with an overall African majority of two-thirds in the security forces.

Although the new mounted unit is just over one year old, Greys' Scouts are actually part of Rhodesian tradition. The first Greys' Scouts - named after founder George Grey - was established in the 1890s during a uprising by the Matabele tribe, a branch of the militant Zulu tribe.

The unit played a major role in the whites' victory, fighting in all major battles and playing the key role in the "Relief of Salisbury," which finally squashed the rebellion.

The revived unit had to prove itself all over again before gaining acceptance from skeptical officials. Starting from scratch on the fields outside Ikomo Barracks, 30 miles from Salisbury, a small group of men who put forward the concept built all the facilities - barracks, offices, stables, blacksmith shop and saddlery.

They scrounged for horses and brought jockeys in to help retrain the animals for combat. Officials also stipulated that all members be volunteers, which led to a hard-sell recruiting campaign to persuade troops to transfer.

Now the mounted unit is the most publicized in the army. It doubled its horse count through unsolicited donations from farmers in Rhodesia and neighboring South Africa after gaining prominence. Capt. Stevens said there is a long waiting list of men who want to join.

Although the strength of the unit is classified, estimates range around 350, with almost twice as many horses.

The only handicap with the animals is their fear of big game in the African bush, especially lions and elephants, Stevens said.

"Otherwise I don't know why the army waited this long to revive the scouts" he said. "If we had been around earlier, the war might not have escalated to this point."