Vital to the survival of Ethryke, and perhaps all of southern Doras Edrossi, the Ethrykian government led by Netyre Loeron Malos sent a call to arms to every single city-state and village territory that they could reasonably muster. Of the nearly twenty nations called, five initially answered the call; in order of acceptance, they were Ceryne, Lavos, the village territory of Efugio, the lordship of Valraenos, and Meyron. Most notably, Meyron did not stay in the war very long, and dropped out after the Battle of Ethryke, thinking the cause to be wholly lost. In response, the Ethrykians summoned the Kingdom of Andoras to support them -- and to everyone's surprise, they accepted the call, landing their first soldiers on the opposite continent in 298 AC. The Andorasi were instrumental in beating back the Zaentovi whom were close to almost completely annexing Ethryke and Efugio, and over the course of the grueling 17 year war, a stalemate was slowly turned into a winning war for the Ethrykian Alliance, and the Treaty of Lavos in 310 AC ensured that the Zaentovi would never dare try to conquer the Leyse Woodlands again.
"The Governed Coalition"
While under the guise of the Ethrykian Alliance, all nations agreed to be centrally led and directed by the best commanders and diplomats from all over the world, and primarily led by Ethryke. Because keeping order in a hellish war for nearly 2 decades would be difficult, the coalition took the form of a government, ensuring that everyone received their fair share during the war. For example, in 308 AC, as the war neared its conclusion, Andoras was suddenly hit with an economic failure as a result of their failure to produce several crops that year, euralaya being among them. As a result, all of the nations in the coalition pledged to donate as much money as they could, bringing Andoras out of debt and back on its feet just in time for the Massacre of the Falls and the Sacking of Ozaento.
Without a doubt, the Ethrykian Alliance brought all nations under its banner closer together, and it survives in some form sans the Kingdom of Andoras in the Drakonian Union, an obscure but intact proclamation that guarantees any outsider war from another power not located in southern Doras Edrossi would be met with resistance from every nation and territory in the region, in an effort to maintain the peace. Prior to the War of Woods, the city-states treated each other as competing rivals; after, as allies who had to stick together, lest they be picked off one by one.
Another notable effect is the formation of other such alliances in other wars. In the Thysian Conflict, for example, other city-states nearly joined the conflict against the Kingdom of Andoras, but decided against it, as the war was too brief and technically Thysia's fault.
Finally, it brought the alien nations of Thauros and Yalende into notable status. The Thaurosians and the Yalendans have been notoriously isolated since they were known of, but fought their own personal war with the Zaentovi, often considered a separate but equal part of the War of Woods. Their own alliance, consisting of just the two of them, was well-fortified, but ill-equipped to wage the offensive side of war. The Ethrykian Alliance, in the final days of their war, supported them by beating back the Zaentovi, thereby improving the likelihood of victory for both alliances. As a token of their gratitude, they opened their borders, but beyond that remained just as isolated and mysterious as they had been before.