Emicho I was a son of Otto, the founder of the Ottonian line of the House of Nassau. After Otto died in 1290, his sons fought a length dispute over the inheritance. In 1303, the three remaining sons divided the Ottonian lands. Henry, the eldest brother, received Nassau-Siegen, with Ginsburg and the Lordship of Westerwald. John received Nassau-Dillenburg, with Herborn, Haiger and Beilstein. Emicho received Nassau-Hadamar, including Hadamar itself, the Esterau, the Nassau share of the Lordship of Driedorf and the justice over Ellar, the Ottonian share of Dausenau and Ems and some dispersed possessions. As recently as 1290, the Lords of Greifenstein, who were co-owners of Driedorf, had forced Henry and Emicho to demolish two of their castles in Driedorf. On the other hand, a treaty closed in Wetzlar promised an end to the Greinfenstein's resistance to the Nassau expansion in the eastern part of the Westerwald. In 1316, Emicho finally managed to purchase the Greifenstein share of Driedorf for 250 marks.
On 18 December 1320 Emicho purchased a model farm from the CistercianEberbach Abbey. This farm was located on the left bank of the Elbbach, opposite Hadamar. The transaction includes the St. Giles church in Hadamar; the abbey retained various other properties in Niederhadamar, Faulbach and Niederzeuzheim. Emich expanded the farm to a water castle named Hadamar Castle, and built a new farm to the south of the castle. He moved his residence to Hadamar Castle. In 1324, Emperor Louis IV granted city rights, modeled on Frankfurt, to Hadamar and Ems. This allowed Emicho to fortify Hadamar with a city wall and a moat surrounding both the town and his castle. The move to Hadamar was probably intended to make it easier to secure his interests in the County of Dietz and to continue purchasing property and rights from the House of Dietz, which was continually in financial difficulties. From 1317, Emicho acted as guardian of Count Gottfried V of Dietz, whose bad financial management had caused the decline of his county. In 1324, Emicho negotiated with Count Gottfried V of Dietz about the intended marriage of Emicho's daughter Jutta with Gottfried's son Gerhard VI. Emicho demanded extended guardianship rights over the County of Dietz, which was already owed him a considerable amount of money. When Gottfried reached adulthood in 1332 and Emicho's guardianship ended, Gottfried transferred his rights over Hadamar and the village of Dehrn to Emicho. On 28 March 1337, Gottfried of Dietz mortgaged the district of Ellar, which he had acquired this district only four years earlier from the Lords of Merenberg, for 1450 Limburgish marks to Emicho's son John. On 4 April 1334, only two months before his death, Emicho transferred the Court and Castle of Hadamar to Archbishop Baldwin of Trier, who gave it back to him as a fief.
Mining rights
On 26 February 1298, King Adolph of Germany mortgaged the rights to the Ratzenscheid mine near Wilnsdorf in the Siegerland area and the other silver mines in the Nassau territory to his cousins Henry and Emicho for 1000 marks worth of pennies from Cologne
John's inheritance
Emicho's younger brother John was captain in the army from Nassau and Mainz that fought in the decisive Battle of Wetzlar that ended the Dernbacher Feud on 10 August 1328. John fell in that battle. Emicho refrained from his share in the inheritance, in favour of his elder brother Henry.
Marriage and issue
Before 1297, Emich married Anna, the daughter of Burgrave Frederick III of Nuremberg and his second wife Helen, the daughter of Duke Albert I of Saxony. They had at least eight children:
Anna, married before 1332 to Count Kuno I of Falkenstein
Jutta, married before 1324 to Count Gerhard VI of Diez
John, Count of Nassau-Hadamar from 1334 to 1365
Emicho II, from 1328 to 1336 canon in Mainz, from 1337 to 1359 co-ruler of Nassau-Hadamar
Margaret, married before 1349 to a Count Hohenberg
Margaretha, a nun in the Poor Clares nunnery in Nuremberg
Emicho died on 7 June 1334. His widow reached a compromise with her son John in 1336, in which she received the imperial Kammerstein Castle as her jointure, plus several manors in Franconia. She would also receive income in kind from John, from his possessions in Laurenburg, Dausenau, Hadamar, Nentershausen and the bailiwick of Weidenhahn and from farms and land in Hadamar, Zeuzheim and Heftrich. She resided at Hadamar castle until 1349, then moved to Kammerstein Castle, where she died between 1355 and 1357.