An important theme of the novel The Shadow Lines is the concept of nationalism that is gaining ground in today’s world. The author has held the extreme form of nationalism responsible for many a problem these days. The separatist and secessionist tendencies are the outcome of it. Love of the country, passion inspired nationalism and intoxication of patriotism cannot but lead to jingoism. Thus nationalism which had and which has great uses can become the greatest obstacle to world unity and world peace. This tribal instinct has been magnified beyond all measures resulting in political and economic megalomania. And the novel in its enthusiasm to prove the point has gone a little too far to proclaim that nationalism is a defunct force and in this background Tha’mma is ridiculed as ‘a still surviving specimen of fossilized nationalism.