The Battalion had no flash between its formation in 1959 and 1968

In 1968 C Company produced a flash for its teams to wear at All Army Shooting Competitions. In keeping with C Coys' historic past, the flash was designed with a representation of the 1920 burning of the Custom House with the letter 'C' underneath. Soon after it was decided that all five sub-units should wear flashes. The design agreed was a phoenix rising from five tongues of flame representing the five companies.

Underneath the phoenix each Company added their own representation in keeping with each Companys' past: A Company, a pikehead, B Company a laurel wreath, C Company kept the Customs House, D Company using the quill and sword and E Company adopting crossed spears. Headquarters Company had the phoenix with three castles, the three castles being from the Dublin City coat of arms.

In 1986 it was felt that the unit needed a more cohesive identity with only one flash for all the sub-units. The blue 'three castles' flash was designed in keeping with the unit identity as the City of Dublin Battalion.