Theodosius had fallen ill, probably because of…

King Asin again attacks Goguryeo in 394, and is again defeated.

Yao Chang soon dies, and Yao Xing succeeds him, although not initially, as he keeps his father's death a secret and entrusts the troops to his uncles Yao Xu and Yao Shuode and his brother Yao Chóng, while preparing a campaign against Former Qin.

Yao Xing had hoped to keep his father's death a secret, but Fu Deng receives news of it anyway and immediately prepares a major attack against Later Qin.

Fu Deng has his brother Fu Guang defend the base of Yongcheng (in modern Baoji, Shaanxi) and …

…Fu Chong defend the base of Hu Kong Castle (in modern Xianyang, Shaanxi).

In his anxiety, he has not ensured that his army has a sufficient water supply.

Yao Xing sets up his army at nearby Mawei to prevent Former Qin forces from reaching the river near Mawei, and Former Qin forces are stricken by thirst, but still fight harder.

Yao Xing initially orders Yin to be cautious, but Yin, realizing the trouble the Former Qin forces are already in and believing that morale would be destroyed if he undertook a cautious strategy, fights back fervently, and the Former Qin forces collapse.

Upon hearing the defeat, Fu Deng's brother Fu Guang and son Fu Chong abandon the two bases that they are holding, and Fu Deng is unable to recapture them.

He now seeks help from the prince of Western Qin, Qifu Gangui, who sends a relief force headed by Qifu Yizhou.

As Fu Deng seeks to join up with Qifu Yizhou, Yao Xing ambushes and captures him, and then executes him.

He disbands Fu Deng's troops and gives Fu Deng's Empress Li to Yao Huang.

Fu Deng's crown prince Fu Chong assumes the imperial title and attempts to resist Later Qin a few months longer, but dies in battle against Western Qin later in the year after Qifu Gangui turns against him, ending Former Qin.

Later Qin assumes nearly all of Former Qin's remaining territory.

Epiphanius of Salamis, a heresiologist who is a strong defender of orthodoxy, known for tracking down deviant teachings (heresies) wherever they can be traced, attacks Origen's followers during a visit to Palestine in 394 and urges the Bishop of Jerusalem to condemn his writings. (Origen's writings will eventually be condemned in 553 at the Fifth Ecumenical Council.)

Arbogast conducts a successful campaign in the winter of 393-394 against the Ripuarian Franks, the Chamavi (a Germanic tribe associated with the Franks), and along the Rhine.

Theodosius marches west in May 394 to suppress the revolution.

As in 388, he will make his way toward the Danube and then the Sava with his powerful army.

His force consists largely of barbarians and their allies, one of whose leaders is the German-born Roman general Flavius Stilicho, who in 385 had been appointed count of the domestics (commanding the Emperor's household troops) and in or before 393 had been named master of both services (i.e., commander in chief of the army).

Following Stilicho’s service on an embassy to the Persian king Shapur III, Theodosius had in 384 arranged the marriage of his favorite niece Serena, whom he had adopted as his daughter, to Stilicho, then an upcoming military officer, ensuring his loyalty to the House of Theodosius in the years ahead.

Stilicho has become the enemy of Rufinus, a native of Gaul who had risen to the rank of praetorian prefect of Illyricum, because of a difference of opinion about the treatment of some barbarian invaders in 389.

Theodosius' sons Arcadius and Honorius stay behind in the capital.

Arcadius, who had been given the right to promulgate laws independently, is supposed to direct the government in the East.

Theodosius first meets the forces of the usurper Eugenius, commanded by Arbogast, at the Frigidus River (modern Vipava River) on the eastern border of Italy, between Aquileia and Emona.

Theodosius' advance guard, composed almost entirely of Visigoth federates under Alaric on September 5, 394, suffers heavy losses during an attempted breakthrough and is only saved by nightfall.

The emperor ventures to attack the following day, however, and is victorious, due chiefly to the brilliant tactics of Stilicho.

The Battle of the Frigidus is part of a trend towards using increasing percentages of barbarian troops, especially in the west, where it will led to the weakening of the empire itself.

Eugenius had represented the last opportunity for the Pagans and the senatorial class to oppose the Christianization of the Empire.

Arbogast commits suicide immediately after the defeat, as does Nicomachus Flavianus, while Eugenius is held for execution as a criminal, his head afterward being displayed in Theodosius' camp.

Theodosius following the deaths of these three shows himself lenient and strives to achieve the settlement between opposing forces that is necessary to strengthen imperial unity.

He promotes Stilicho to generalissimo.

Baekje has begun to crumble politically after several heavy defeats, and Asin’s leadership comes under doubt.

Asin loses to Goguryeo again in 395, and he is eventually pushed back to a front along the Han River, where Wiryeseong, Baekje's capital city, is located in the southern part of modern day Seoul.

Gwanggaeto himself attacks and conquers Biryu, a small nation located in central Manchuria, during a campaign against Baekje in 395. (Its exact location is not known but it was not very far from the Songhua River.)