CC Madhya 15.32

vijayā-daśamī — laṅkā-vijayera dine
vānara-sainya kailā prabhu lañā bhakta-gaṇe
Word for word: 
vijayā — victory; daśamī — tenth day; laṅkā-vijayera dine — on the day celebrating the conquering of Laṅkā; vānara-sainya — monkey soldiers; kailā — arranged; prabhu — Śrī Caitanya Mahāprabhu; lañā bhakta-gaṇe — taking all the devotees.
Translation: 
On the day celebrating the conquest of Laṅkā — a day known as Vijayā-daśamī — Śrī Caitanya Mahāprabhu dressed up all His devotees as monkey soldiers.