Arthashastra
वर्षति मरु प्रायं चतुर् अङ्ग बलो यायात् ॥
Against a desert, one should march during the rainy season with all the four constituents of the army (elephants, horses, chariots, and men).
english translation
varSati maru prAyaM catur aGga balo yAyAt ॥
hk transliteration by Sanscript