He might, therefore, have expected gratitude from his adopted country; but shortly after he returned to Nice he was placed under arrest, and was imprisoned in a fort near Antibes.
The causes of this swift reverse of fortune were curiously complex.
The Robespierres had in the meantime been guillotined at Paris (July 28th, or Thermidor 10th); and this "Thermidorian" reaction alone would have sufficed to endanger Buonaparte's head.

But his position was further imperilled by his recent strategic suggestions, which had served to reduce to a secondary _role_ the French Army of the Alps.
The operations of that force had of late been strangely thwarted; and its leaders, searching for the paralyzing influence, discovered it in the advice of Buonaparte.

Their suspicions against him were formulated in a secret letter to the Committee of Public Safety, which stated that the Army of the Alps had been kept inactive by the intrigues of the younger Robespierre and of Ricord.

Many a head had fallen for reasons less serious than these.

But Buonaparte had one infallible safeguard: he could not well be spared.