Unfortunately, the unit attracted all kinds of fire from the enemy. I guess the best idea is to find a quieter crossing point and provide support units to help protect them.
Actually I use bridging units to establish bridgeheads. If you leave a bridging unit over a river and get no troops through, it's only natural that as the turn advances the enemy is going to primary it...do it all the way around. Set things up so the bridging units gets to the river before any of your other troops has moved. As soon as the bridging unit is on the river, the bridge is set up and you can pass your units to the other side instantly. That way you get to cross almost uninterrupted and with much less enemy opposition.
Dunno about you guys but for me in scenarios like the Barbarossa one, a couple bridging units are a must, one in the northern pzgruppe, other in the southern. Too many rivers to cross in the map and too tight a schedule for a decisive win, for you to take the luxury of losing whole turns because you couldn't capture a vital bridge in the map because a couple bad attack rolls (or because an unspotted enemy arty caused your whole attack to go FUBAR)
"Look at me! look at me!!!
Not like that! NOT LIKE THAT!!!"