Has any war in recorded history ever resulted in the complete annihilation (civil and military) of an enemy - all of them killed with no survivors?

There is the [Amalek]s1 that there was religious order to kill everywhere.

From man unto woman, from infant unto suckling, from ox unto sheep, so that the name of Amalek not be mentioned even with reference to an animal by saying "This animal belonged to Amalek".

Judges 20:48

And the men of Israel turned again upon the children of Benjamin, and smote them with the edge of the sword, as well the men of every city, as the beast, and all that came to hand: also they set on fire all the cities that they came to.

Jeremiah 18:21

Therefore deliver up their children to the famine, and pour out their blood by the force of the sword; and let their wives be bereaved of their children, and be widows; and let their men be put to death; let their young men be slain by the sword in battle.

Numbers 31

"Now therefore kill every male among the little ones, and kill every woman that hath known man by lying with him. But all the women children, that have not known man by lying with him, keep alive for yourselves"

So it seems that total annihilation (with the possible exception of virgins taken as slaves) was the standard procedure.

History is full of those too...

The Punic war for example...

https://en.wikipedia.org/wiki/Punic_Wars

There are many more. .but this one jumps right out.

The war of the Qing dynasty against the Dzunghars (an Oirat Mongol tribe) during the era of the Qianlong Emperor resulted in the complete extinction of the Dzunghars.

Wikipedia:

The Qianlong Emperor then ordered the genocide of the Dzungars, moving the remaining Dzungar people to the mainland and ordering the generals to kill all the men in Barkol or Suzhou, and divided their wives and children to Qing forces (...)

In his account of the war, Qing scholar Wei Yuan, wrote that about 50% of the Dzungar households were killed by smallpox, 20% fled to Russia or the Kazakh Khanate, and 30% were killed by the army, leaving no yurts in an area for several thousand li, except those of the surrendered. Clarke wrote 80%, or between 480,000 and 600,000 people, were killed between 1755 and 1758 in what "amounted to the complete destruction of not only the Dzungar state but of the Dzungars as a people." 80% of the Dzungars died in the genocide.

53BC, Caesar launches a campaign of annihilation against the Eburones (De Bello Gallico book VI) in revenge for their part in destroying a Roman garrison. Regardless of the outcome, the stated intent was to wipe out the people and their name from history. Ironically they survive in his writings.

All the local animals were killed, all crops harvested and carried off, neighbouring tribes encouraged to plunder, every village, dwelling, town destroyed - no prisoners.

Whether you call them states or not, several cities were wiped out by the Mongols under Genghis and their entire populations killed. The city of Merv is an example. Destroyed by Tolui in 1221.

The criteria set forth in the question are quite difficult to satisfy. If you go back far enough certain tribes would have been so small that any warlike confrontation would ensure that the group could not survive as such. But then again, "everyone killed" is not really likely in those conditions, as most of the time the women were treated as spoils of war. That is, not killed but taken.

One thing that will probably seen as very contentious is the sometimes so-called genocide of the native Americans. Obviously, some "Indians" are still around, so the American Indian Wars would not satisfy the criteria – either for the purposes of this question or a scholarly definition of genocide?

Apart from "Indians" being a really big heading to classify "500 Nations" there are a few examples very worth noting and considering in that regard.

One of these would the Beothuk, although with some caveats:

Scholars disagree in their definition of genocide in relation to the Beothuk, and the parties have differing political agendas. While some scholars believe that the Beothuk died out due to the elements noted above, another theory is that Europeans conducted a sustained campaign of genocide against them.

Many of the settlers in California during the Gold Rush were extremely hostile towards Indians and the California government adopted anti-Indian policies. In fact some people write about the "California Genocide" in that era.

https://en.wikipedia.org/wiki/California_Genocide[1]

A number of California tribal groups suffered large population decreases from attacks by the immigrants to California, in addition to losses from diseases.

Some of the tribes may have become split up and/or joined with other tribes, but as far as I know most of the pre-Gold Rush tribes still have their tribal governments.

The Yana people in California had about 1,500 to 3,000 people in four subgroups before the Gold Rush. The southernmost subgroup, the Yahi, numbered about about 400 before the Gold Rush and are now extinct. Many starved when the Gold Rush destroyed their food sources and many were killed by the settlers. Over a hundred Yahis were massacred in 6 separate incidents in 1865, 1866, 1867, and 1871 and they were believed extinct. But a small group survived and slowly died off until the last survivor revealed himself in 1911.

Tasmania was inhabited by thousands, not to be too specific, of Aboriginals before the first European settlement in 1803. Decades of disease and conflicts with Europeans reduced their population to about 200 in 1833 who were moved to a camp on Flinders island, in 1847 the 47 survivors were moved to another camp. The last pure blood Tasmanian is considered to have been either Truganini (1812-1876) or Fanny Cochrane Smith (1834-1905).

So H.G. Wells, in The War of the Worlds (1897) Chapter 1, "The Eve of the War", wrote:

And before we judge of them too harshly we must remember what ruthless and utter destruction our own species has wrought, not only upon animals, such as the vanished bison and the dodo, but upon its inferior races. The Tasmanians, in spite of their human likeness, were entirely swept out of existence in a war of extermination waged by European immigrants, in the space of fifty years. Are we such apostles of mercy as to complain if the Martians warred in the same spirit?

https://www.gutenberg.org/files/36/36-h/36-h.htm[2]

However, in 2016 the number of people of partial Tasmanian Aboriginal descent is estimated to be about 6,000 to 23,000.

https://en.wikipedia.org/wiki/Aboriginal_Tasmanians[3]

Even though the total extermination of an enemy population has rarely been achieved, many enemy states have been totally destroyed. For example, the Confederate States of America never surrendered but instead was totally conquered by United States forces.

During the Beaver Wars of the 17th Century the Iroquois totally destroyed a number of tribes, reducing their populations to three classes:

1. the dead.
2. fugitives seeking asylum with other tribes and gradually assimilating into them.
3. captives of the Iroquois who gradually became assimilated into Iroquois society.

By 1652 the Iroquois had wiped out the Huron, Petun, Erie, and Neutral Nations.

Added 12-19-2018:

Among recognized modern independent nations with diplomatic relations with other countries the highest fatality rate was suffered by Paraguay in the War of the Triple Alliance from 1864–1870, with allegedly over 50 percent of its prewar population including civilian men, women, and children, killed.

Thus it seems likely that any possible examples of totally exterminated groups are likely to have been small tribes with much smaller populations than Paraguay.