Sentence:  For the capricious and uncertain favor of this the only marriageable young lady in the district, all the susceptible and unattached cowboys (of which class the population almost wholly consisted) strove together eagerly and without ceasing, <WSD>mavericking</WSD> right and left everything they could lay their hands on, with a running brand L I L, until, when the tenderfoot she had all along been engaged to came out and married her, she brought him great herds of L I L cattle, with which they gayly set up a ranch beneath the noses of the forlorn celibate community. 
Meaning of the word marked with <WSD> tags:  To take an unbranded range animal.