The Heike Monogatari has been translated into English at least five times. Below an overview of the most prominent translations.
Sadler's pioneering translation of the Heike Monogatari was published in two parts. Volumes 1 through 6, up to chapter 7 were published in the 46th edition of the Transactions of the Asiatic Society of Japan in 1918, while the remainder of the work was published in the 49th edition in 1921. Sadler's translation was based on the Rufubon (流布本) edition. His full translation is available here.
Sadler, A. L. (1918-1921). The Heike Monogatari. Transactions of the Asiatic Society of Japan. 46.2 (1918): 1–278 and 49.1 (1921): 1–354.
Kitagawa, H. and Tsuchida, B.T., eds. (1975). The Tale of the Heike. Tokyo: University of Tokyo Press.
McCullough, H.C. (1988). The Tale of the Heike. Stanford: Stanford University Press.
Watson, B. and Shirane, H. (2006). The Tale of the Heike (abridged). New York: Columbia University Press.
Tyler, R. (2014). The Tale of the Heike. New York: Penguin Books.
The famous opening paragraph of the Heike Monogatari and some of its translations in English:
Gionshōja no kane no koe, Shogyōmujō no hibiki ari.
Sarasōju no hana no iro, Jōshahissui no kotowari wo arawasu.
Ogoreru mono mo hisashikarazu, tada haru no yoru no yume no gotoshi.
Takeki mono mo tsuwi ni wa horobin(u), hitoeni kaze no mae no chiri ni onaji.
The sound of the bell of Gionshoja echoes the impermanence of all things.
The hue of the flowers of the teak tree declares that they who flourish must be brought low.
Yea, the proud ones are but for a moment, like an evening dream in springtime.
The mighty are destroyed at the last, they are but as the dust before the wind.
The sound of the Gion Shōja bells echoes the impermanence of all things;
the color of the śāla flowers reveals the truth that the prosperous must decline.
The proud do not endure, they are like a dream on a spring night;
the mighty fall at last, they are as dust before the wind.
The Jetavana Temple bells
ring the passing of all things,
Twinned sal trees, white in full flower,
declare the Great Man's certain fall.
The arrogant do not long endure:
They are like a dream one night in spring.
The bold and brave perish in the end:
They are as dust before the wind