Fateh!
You know that fateh means victory, and Fatehnama means Epistle of Victory or Letter of Victory. Here is brief and simple background piece. If you want to know more just type Fatehnama in the Google search engine. The original name by the way was Zafarnama, with the name changed in a subsequent era.
Fatehnama
From
Sikh-heritage -- this little bit of a longer document
The 'Fatehnama' was read by Aurangzeb, and he deeply regretted his actions and the unjust orders and counsels which he had given to the Subas of Lahore and Sirhind and the hill Warlords, to destroy Guru Ji and Anandpur. So he immediately ordered that no one should stand in the Guru's way. Aurangzeb stating his remorse at the false information relayed to him, against Guru Ji, wrote a reply to the 'Fatehnama'. He also desired to meet Guru Ji. This letter of Aurangzeb reached Guru Ji at Kangar, and it pleased Guru Ji, who wrote another letter to Aurangzeb which is know as "Zafarnama" (Epistle of Victory). Only a few parts of this letter "Fatehnama" are available, the translation of which is given here under.