War caging in the Horn of Africa, involving the biggest fight ever between two independent black Africa states and probably the continent's worst secessionist struggle, have left tens of thousands dead, hundreds of thousands uprooted and massive destruction.

But they have resolved nothing and all the parties appear as determined as ever to fight on for their respective nationalist causes.

Ethiopia's war with Somalia in 1977-78 and its continuing battles with Eritrean separatists are classic examples of nationalism on the African continent today and the limitations of Marxist ideology in this region.

For the Soviets and Cubans, nationalism is the major obstacle to their design of a federation of Marxist states straddling the strategic straits of Bab el Mandeb at the entrance to the Red Sea.

With the revolution in Ethiopia in 1974 and the Eritrean independence movement becoming more radical, all of the three main antagonists -- Eritreans, Somalis and Ethiopians -- have officially adopted Marxism-Leninism as their guiding principle of political organization and economic development.

Yet the three have never been further apart and the best efforts of the Soviets and Cubans to find solutions to the conflict of opposing nationalism tearing apart this northern corner of the continent, the Horn of Africa, have failed.

After nearly five years of intense warfare, a new Marxist Ethiopia has emerged from the ruins of the ancient Ethiopian empire, battered and bankrupt but still intact. Thanks to massive Soviet arms deliveries and more than 20,000 Cuban combat troops, Ethiopia has been the ultimate victor in all the big battles over the size and shape of the old feudal empire fought against Somalia and the Eritrean movement.

But Ethopia has not yet won the war. Neither the struggle with the Somalis over the Ogaden region in the southeast nor the battle with the Eritreans over the northernmost province has been resolved and the fighting seems far from over

The dimensions of the conflicts numb the mind. The Somalis, Eritreans and Ethopians together have fielded somewhere between 350,000 and 400,000 armed soldiers and guerrillas -- the Ethopian revolutionary Red Army and militia alone numbering around 250,000 -- on behalf of their respective causes.

After pouring $1 billion worth of arms into Somalia, the Soviet Union switched sides and proceeded to pour another $1 billion worth into Ethiopia.

The death toll as a result of the large-scale wars made possible by these huge arms shipments and mass mobilizations of troops is incalculable, but it must run into the many tens of thousands. Some individual battles in the Ogaden and Eritrea are known to have resulted in thousands of casualties and to have involved protracted hand-to-hand fighting for towns and tank duels such as black Africa has never seen.

Neither the civil war in eastern Nigeria, nor conflicts in Angola or the southern Sudan has equaled the ferocity of fighting in Eritrea, where the Ethiopians finally resorted to the Chinese tactic of throwing human waves of militiamen against the guerrilla positons despirt the high cost in lives.

Refugees from Eritrea and the Ogaden number in the hundreds of thousands. Around 200,000 Eritreans have fled into neighboring Sudan, and the same number or more Somalis from the Ogaden have moved to Somalia. Their leaders charge that Ethiopia has purused a policy of "genocide."

The Ethiopians deny this and reply that both the Somalis and Eritrean guerrillas have inflicted indiscriminate damage on schools, hospitals, power stations, water facilities and development projects, causing enormous hardship to their own peoples.

Ethiopia is settling 450,000 war victims in 169 new villages in just the southern province of Bale and has another 150,000 on its hands in Sidamo Province. Both areas were heavily infiltrated by Somali guerrillas and army regulars, according to the Ethiopians, and were actually partly taken over in the 1977 Somali offensive.

The head of the Ethiopian Relief and Rehabilitation Commission, Shamalis Adugna, estimates the cost of repairing war damage in the south and east at $390 million. He also says that about $30 million is needed for just basic repairs to public facilities in Eritrea.

In the northern province, the Ethiopians after a fitful, year-long offensive have recaptured all but two of the main twons from the Eritrean guerrillas. Only Nakfa and Karora in northern Eritrea remain to be retaken.

But the Eritreans are still far from being a spent force and have simply reverted from conventional warfare to their old guerrilla tactics, hitting the stretched out Ethiopian forces and supply lines just as they were doing with deadly effect in 1975.

Even the provincial capital of Asmara is not safe from attack, although the first foreign correspondents to visit Eritrea for years recently reported life slowly was rturning to normal there, as in the retaken key towns of Keren and Massawa.

But since then, other unconfirmed reports reaching Addis Ababa say guerrillas have shot down an Antonov transport plane as it was landing at Asmara airport as well as another smaller aircraft and even have raided the provinical capital.

Apparently something happened, for after promising to take me to Asmara, Keren and Massawa, the Ethiopian government suddenly canceled the trip for "technical reasons."

Some Ethiopians privatly concede a military solution to the Eritrean problem is impossible and a political one must be found. But efforts to establish even a basis for discussions have evaded everyone -- Cubans, Soviets, South Yemenis, Sudanese, Tanzanians and East Germans.

Three meetings between the Ethiopian government and Eritrean leaders in East Berlin last year all failed because, as one Ethiopian official put it, "they [the Eritreans] said we cannot discuss anything except total independence. They even refused to speak anything but Arabic," he remarked.

The main Ethiopian languages are Amharic, Gallinya and Tigrinya, the latter widely spoken in Eritrea.

The new military government under Lt. Col. Mengistu Haile Mariam is willing to give Eritrea local autonomy similar to that being promised in principle to all the other main regions of the country, but it is also including special status such as a federation.

Repeated attempts by Sudanese President Jaafar Nimeri to mediate the Eritrean dispute have also failed, despite his experience in settling the civil war in southern Sudan.

When asked about the possibility of future talks with the Eritreans, Ethiopian officials at the Foreign Ministry reply curtly, "We are not prepared to talk to them."

In the Ogaden, Somali guerrillas again are harassing Ethiopian and Cuban supply lines and convoys. They reportedly control much of the barren countryside, if they no longer occupy any major town.

Most of the roughly 15,000 Cuban troops still serving in Ethiopia are now garrisoned in the Ogaden, holding the line there while the main Ethiopian forces fight to reconquer Eritrea.

Irritated by the stepped-up Somali guerrilla attacks in the Ogaden, the Ethiopians repeatedly bombed Somalia over the past six months and Mengistu gave what he said was a "final warning" to the Somali government.

The possibility of yet another major confrontation between Ethiopian and Somali forces thus cannot be pulled out.

And so war goes on in the bitterly divided Horn of Africa, with neither the Somalis, Ethiopians or Eritreans showing any willingness to compromise and lower the banner of their respective nationalist causes.