144258
Cavalry units were again brought forward on September 15 to support the attack on Flers-Courcelette , but were not drawn into the fighting and played no further part in the Battle of the Somme except as labour units in reserve .
 Cavalry, Somme
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 Cavalry, Somme