In 316, Turgon's sister Aredhel became restless and wanted to leave
Gondolin after living there for 200 years. Turgon agreed to let her
visit their brother Fingon though he was reluctant to allow anyone who
knew Gondolin's location to wander abroad. But Aredhel chose a different
destination, became separated from her escort, and eventually got lost
in the woods of Nan Elmoth. Nan Elmoth was the home of Eol the
Dark Elf who was a renowned smith. He used enchantments to prevent
Aredhel from finding the way out of the woods and led her to his home.
Aredhel married Eol and they had a son named Maeglin who also became a
smith. Maeglin was intrigued by his mother's stories of Gondolin and
especially by the fact that his uncle Turgon had no male heir. In
400, Maeglin convinced Aredhel to return to Gondolin while Eol was
away, but Eol followed them and discovered the Hidden Way. Turgon at
first welcomed Eol but said that he was required to remain in Gondolin
since he knew its location. Eol refused and when threatened with the
alternative of death Eol tried to kill his son as well but hit his wife
with his javelin instead.
Aredhel died of a poisoned wound and Eol was thrown to his death from
the city walls the next day. Maeglin silently observed his father's
execution, and Idril - Turgon's daughter and heir - began to distrust
Maeglin. Maeglin became enamored of Idril, but first cousins did not
marry and his interest made Idril dislike him more. Maeglin
impressed many other Gondolindrim with his skills as a smith, and he
taught his craft to others and gathered a number of followers. They
mined in the Encircling Mountains for ores and metals to use to forge
strong weapons. Maeglin built the Seventh Gate of Gondolin, the Gate of
Steel. He rose to a high position and became a close counsellor of the
King. In 455, Morgoth broke the Siege of Angband and in the
Battle of Sudden Flame Morgoth's forces made inroads into Beleriand.
Turgon's father Fingolfin rode to Angband and challenged Morgoth to
single combat and after a long struggle Fingolfin was killed. Thorondor,
the King of the Eagles, brought Fingolfin's body to a mountaintop
overlooking Gondolin from the north and Turgon built a cairn for his
father.
Gondolin remained hidden and Turgon did not send any forces into battle.
But Turgon realized the danger posed by Morgoth and he sent messengers
to seek the help of the Valar. They travelled down the Sirion to the
Isle of Balar and built ships to sail westward, but they did not find
the Undying Lands and few of the messengers returned to Middle-earth. In
458, two young Men named Hurin and Huor became lost in Dimbar south of
Gondolin after a skirmish with Orcs. The brothers were of the House of
Hador - one of the three Houses of the Edain allied with the Elves
against Morgoth. Huor was only 13 years old and Hurin was in his late
teens. Thorondor sent two Eagles to bring Hurin and Huor to Gondolin. Ulmo
warned Turgon through dreams that Gondolin's fate was tied to the sons
of the House of Hador. Turgon welcomed the brothers and they stayed in
Gondolin for about a year. Turgon became fond of them and when they
asked to leave he agreed despite his law forbidding the departure of
anyone who came to Gondolin. They did not know the exact location of
Gondolin and they swore not to reveal what they knew. The Eagles
returned Hurin and Huor to their people but some suspected where they
had been and Morgoth's spies heard the rumors.
In 468, Turgon learned that Maedhros, son of Feanor, was forming an
alliance to oppose Morgoth. Turgon's brother Fingon was a part of the
Union of Maedhros. Turgon began to prepare the forces of Gondolin for
battle. In 472, Turgon led forth an army of 10,000
Gondolindrim. He was accompanied by Maeglin as well as his captains
Ecthelion and Glorfindel. In the Battle of Unnumbered Tears, Fingon's
forces were surrounded by Orcs on the desert of Anfauglith near Angband.
Turgon came to his brother's aid and found Hurin and Huor with him. But
the tide of the battle turned and Fingon and Turgon were separated.
Fingon was killed by Gothmog, Lord of Balrogs. Hurin and Huor urged
Turgon to return to Gondolin. Then Hurin spoke to Turgon,
saying: "Go now, lord, while time is! For in you lives the last hope of
the Eldar, and while Gondolin stands Morgoth shall still know fear in
his heart." But Turgon answered: "Not long now can Gondolin be hidden; and being discovered it must fall." Then
Huor spoke and said: "Yet if it stands but a little while, then out of
your house shall come the hope of Elves and Men. This I say to you,
lord, with the eyes of death: though we part here for ever, and I shall
not look on your white walls again, from you and from me a new star
shall arise. Farewell!" The Silmarillion: "Of the Fifth Battle," p. 194