Those were on one of Takeda Shingen's famous war banners. Its a quote from the Chinese strategist Sun Tsu (Zi).
風 Swift as the wind
林 Quiet as the forest
火 Conquer like the fire
山 Steady as the mountain
It seems to get translated a little differently depending on who is using/translating it though:
"Takeda also has a flag that basicaly say "Fu-Rin-Ka-Zan" It is a chinese war tactics basically saying Move like a Wind, Sneak up on like Bush, Fight like a Fire, and wait for a chance like a Mountan"
"Alive like the wind, Quiet like the forest, Burning like fire, Unchangeable, like a mountain"
You can see the characters for it here:
That is how it was arranged on Takeda's famous standard which was captured from his son after his defeat at Nagashino.