Assassination has sometimes been the prelude to revolution, but it may be questioned if it has over promoted the cause of liberty.  Most frequently it has served as a pretext for reaction, or a red signal.  In this instance—­as afterwards in 1848—­overt acts of violence made the powers of despotism more alert, and conduced with the half-hearted action of their adversaries to the suppression of the rising of 1820-21.  Byron’s sympathy with the movement seems to have been stimulated by his new associations.  Theresa’s brother, Count Pietro, an enthusiastic young soldier, having returned from Rome and Naples, surmounting a prejudice not wholly unnatural, became attached to him, and they entered into a partnership in behalf of what—­adopting a phrase often flaunted in opposite camps—­they called constitutional principles.  Finally the poet so committed himself to the party of insurrection that, though his nationality secured him from direct attack, his movements were necessarily affected by the fiasco.  In July the Gambas were banished from the Romagna, Pietro being actually carried by force over the frontier; and, according to the articles of her separation, the Countess had to follow them to Florence.  Byron lingered for some mouths, partly from a spirit of defiance, and partly from his affection towards a place where he had enlisted the regards of numerous beneficiaries.  The Gambas were for some time bent on migrating to Switzerland; but the poet, after first acquiescing, subsequently conceived a violent repugnance to the idea, and early in August wrote to Shelley, earnestly requesting his presence, aid, and counsel.  Shelley at once complied, and, entering into a correspondence with Madame Guiccioli, succeeded in inducing her relatives to abandon their transmontane plans, and agree to take up their headquarters at Pisa.  This incident gave rise to a series of interesting letters, in which the younger poet gives a vivid and generous account of the surroundings and condition of his friend.  On the 2nd of August he writes from Ravenna:—­“I arrived last night at ten o’clock, and sat up talking with Lord B. till five this morning.  He was delighted to see me.  He has, in fact, completely recovered his health, and lives a life totally the reverse of that which he led at Venice....  Poor fellow! he is now quite well, and immersed in politics and literature.  We talked a great deal of poetry and such matters last night, and, as usual, differed, I think, more than ever.  He affects to patronize a system of criticism fit only for the production of mediocrity; and, although all his finer poems and passages have been produced in defiance of this system, yet I recognize the pernicious effects of it in the Doge of Venice.”  Again, on the 15th:  “Lord B. is greatly improved in every respect—­in genius, in temper, in moral views, in health, and happiness.  His connexion with La Guiccioli has been an inestimable benefit to him.  He lives in considerable splendour,