Today, the 3rd of Tammuz marks the day when G-d answered Yehoshua's prayer to lengthen the day to ensure victory.
Like the Bible accounts, this is written in the Book of Yashar (Joshua 10:13). Below is the extraction from Sefer HaYashar:
Sefer HaYashar covers in length and detail the wars fought by the sons of Yaakov as well as Israel as a nation. From this book it is clear the strength and might these men had as warriors.